Thames Marathon Swim
HS
From Henley Swim
Event summary
Get ready for an exhilarating day of open water swimming at the Thames Marathon Swim, organized by Henley Swim, taking place on Sunday, August 10th, 2025, in the picturesque town of Marlow, Buckinghamshire. Known for its stunning scenery and vibrant atmosphere, this prestigious event has earned accolades, including being rated the Top-Rated swim by Racecheck and winning several gold awards.
Swimmers can choose from a variety of race distances, including the full 13km marathon swim, a 9km mid-distance challenge, or a 5.5km half marathon, all set against the breathtaking backdrop of the River Thames. Participants will navigate through sections at three different locks, where refreshments will be provided to keep everyone energized. For those looking for a team experience, the Thames Marathon Relay allows three swimmers to tackle the full distance together in a fun and engaging way.
The event village is conveniently located at Higginson Park, where spectators can enjoy the vibrant atmosphere while cheering on their favorite swimmers. With transport provided to the starting points and a beautiful route back to Marlow, this event promises excitement for both participants and supporters alike. Don’t miss out on this chance to be part of one of the most celebrated swims in
Swimmers can choose from a variety of race distances, including the full 13km marathon swim, a 9km mid-distance challenge, or a 5.5km half marathon, all set against the breathtaking backdrop of the River Thames. Participants will navigate through sections at three different locks, where refreshments will be provided to keep everyone energized. For those looking for a team experience, the Thames Marathon Relay allows three swimmers to tackle the full distance together in a fun and engaging way.
The event village is conveniently located at Higginson Park, where spectators can enjoy the vibrant atmosphere while cheering on their favorite swimmers. With transport provided to the starting points and a beautiful route back to Marlow, this event promises excitement for both participants and supporters alike. Don’t miss out on this chance to be part of one of the most celebrated swims in
Thames Marathon Swim
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Reviews
4.83 reviews
LN
Luke Noble
Verified entrant
This reviewer is a verified Find a Race user who purchased a place at this event.
Took part in the 2023 edition · 3 years ago
Lovely bunch of people.
Well organised. Everything seems smooth and fast.
Excellent food stations.
Water entrance and exit at some places could be better. And toilets wanted at break areas.
Overall, brilliant and from what I hear they improve every year
Well organised. Everything seems smooth and fast.
Excellent food stations.
Water entrance and exit at some places could be better. And toilets wanted at break areas.
Overall, brilliant and from what I hear they improve every year
MH
Mark Hyem
Verified entrant
This reviewer is a verified Find a Race user who purchased a place at this event.
Took part in the 2023 edition · 3 years ago
Great Event. Very Well Organised. Super friendly Event
JW
Julie Whittle
Reviewing the 2019 edition · 7 years ago
Well Organised. Long swim but felt very well looked after both before, during and after event. Help getting out at locks, great variety at food stops and plenty kayak/safety support.
Event information
THAMES MARATHON
Approx 13km*
The swim is split into 4 sections. Swimmers will be required to exit the water at the 3 locks (Hambleden, Hurley and Temple ) where drinks and energy snacks will be available.
THAMES MID-DISTANCE MARATHON
Approx 9km*
The swim is split into 3 sections. Swimmers will be required to exit the water at the 3 locks (Hambleden, Hurley and Temple ) where drinks and energy snacks will be available.
THAMES HALF MARATHON
Approx 5.5km
The swim is split into 3 sections. Swimmers will be required to exit the water at the 2 locks (Hurley and Temple) where drinks and energy snacks will be available.
THAMES MARATHON RELAY
Approx 13km*
Each person will swim one 4/5km section of the course and walk two. All team members will be taken to the start of the course with handovers at Hambleden and Hurley Locks, where drinks and energy snacks will be available.
The manageable chunks make these long-distance swims do-able for many different types of swimmer!
Approx 13km*
The swim is split into 4 sections. Swimmers will be required to exit the water at the 3 locks (Hambleden, Hurley and Temple ) where drinks and energy snacks will be available.
THAMES MID-DISTANCE MARATHON
Approx 9km*
The swim is split into 3 sections. Swimmers will be required to exit the water at the 3 locks (Hambleden, Hurley and Temple ) where drinks and energy snacks will be available.
THAMES HALF MARATHON
Approx 5.5km
The swim is split into 3 sections. Swimmers will be required to exit the water at the 2 locks (Hurley and Temple) where drinks and energy snacks will be available.
THAMES MARATHON RELAY
Approx 13km*
Each person will swim one 4/5km section of the course and walk two. All team members will be taken to the start of the course with handovers at Hambleden and Hurley Locks, where drinks and energy snacks will be available.
The manageable chunks make these long-distance swims do-able for many different types of swimmer!
Chip Timing
Finisher Medal
Secure Bag Drop
Merchandise
Finisher Medal
Secure Bag Drop
Merchandise
There are plenty of public car parks in Marlow operating pay and display. We will transport swimmers by coach to the swim start, and they will be able to walk back to their cars after completing their swim.
We encourage swimmers to car share wherever possible. If you are looking for a lift or would like to offer space in your car, please post on Henley Swim Chatter, our Facebook group.
We encourage swimmers to car share wherever possible. If you are looking for a lift or would like to offer space in your car, please post on Henley Swim Chatter, our Facebook group.
Event village in Higginson Park, Marlow. Coaches to take swimmers to start.
Where does the swim start and finish?
The car park and event village will be in Marlow.
The Thames Half Marathon 5.5km will start above Hurley. The start will only be accessible to swimmers or walkers, there will be no vehicle access to the start (disabled swimmers please contact [email protected] to discuss options).
The Thames Marathon full-distance swim will start in Henley. Coaches will drop swimmers to the start.
Both distances finish at Higginson Park, Marlow.
Is there other parking in Marlow?
Yes, there are plenty of public car parks in Marlow operating pay and display
Will there be bagdrop?
There will be a bag drop facility in Marlow. We will tag your bag for identification purposes, and you will need to show your numbered hat to be able to collect your bag after your swim.
Can I swim in a team with a group of friends?
Absolutely, in fact we encourage it. The more people who swim together and look out for each other, the safer the event is. If you wish to swim with friends, please make sure that you all enter the same wave.
Will I be able to wear a tow float?
All swimmers will be required to use a tow float and are advised to get used to swimming with one before the event. You can purchase a discounted Swim Secure tow float when you register
How will you ensure that those who want to do solo swims are able to do so safely?
We have a fully approved safety plan that ensures coverage across the full course throughout the event. In addition ALL swimmers will be required to use a tow-float.
Can I swim non-wetsuit?
We have a limited number of non-wetsuit places available for both the Half Marathon and the Full Marathon. This is to minimise the risk to our safety plan. Wetsuits are important for retaining heat and providing buoyancy. If you would like a non-wetsuit place in the full marathon your application will be assessed by the events team for approval.
Non-wetsuit places sell out very quickly, we recommend applying as soon as registration opens.
How many feed stops will there be ?
There will be 3 feed stops for the full Thames Marathon and 2 for the Half Marathon.
What food will be available at the feed stops?
We will provide a bit of everything for this long-distance swim, including bananas, energy bars, energy drinks, water, some chocolate, sweets, and some salty snacks. If you wish to use energy gel, please bring your own in your tow float, so that you know the particular brand that you use will suit you.
How will the start work (full marathon)?
The slower swimmers will set off first. The faster swimmers will set off after with those expecting to finish under 3 and a half hours setting off last. Swimmers will be dropped at the start ‘swim-ready’ and will get off the coach, walk to the start and straight into the water for a rolling start within their wave time.
How should I choose which wave to enter?
The Thames Marathon will be setting off from Henley from 7.30am. Strong swimmers who are seeking a faster time and who expect to complete the course in under 4 hours (approximately equivalent to a sub 27-minute mile pace) should select waves 7-10. If you expect your time to be under 3½ hours, please select wave 10, between 3½ and 4 hours select wave 7, 8 or 9. Other swimmers should select wave 1 – 6 – these are all mixed ability waves. If you wish to swim with a group, please ensure that you all select the same wave.
There will be a cut-off time of six and a half hours for the full marathon, 5 hours for the mid-distance marathon and three and a half hours for the half marathon, where all swimmers will need to be out of the river. If you anticipate that you will take longer than this, please contact [email protected] before entering.
Are there toilets on the course?
There are toilets at Higginson Park. There are a couple of cafes and pubs near the walking route. Please note that once you have left Higginson Park on the coach, there will be no toilets at the start of either the full or half-marathon.
Can supporters walk the route?
The route is walkable, by following The Thames Path. It is also possible to cycle the route, although there are a large number of kissing style gates where you may have to lift your bikes to get through and it may be difficult with tag-alongs.
Supporters that start with their swimmer at Higginson Park can walk upstream until they meet the swimmers, and walk back downstream alongside them. Alternatively they can stay at the event village or go into Marlow for a coffee, and wait for the swimmers to return.
Supporters can be dropped at the start of the full-distance in Henley by friends or family with their swimmer, and walk the full distance of the course, but there is no parking at the start.
Can I talk to fellow swimmers in advance of the event?
Definitely, we have set up Henley Swim Chatter as a facebook forum, where you are able to discuss anything with fellow swimmers from nutrition and training tips to transport to the event on the day.
The car park and event village will be in Marlow.
The Thames Half Marathon 5.5km will start above Hurley. The start will only be accessible to swimmers or walkers, there will be no vehicle access to the start (disabled swimmers please contact [email protected] to discuss options).
The Thames Marathon full-distance swim will start in Henley. Coaches will drop swimmers to the start.
Both distances finish at Higginson Park, Marlow.
Is there other parking in Marlow?
Yes, there are plenty of public car parks in Marlow operating pay and display
Will there be bagdrop?
There will be a bag drop facility in Marlow. We will tag your bag for identification purposes, and you will need to show your numbered hat to be able to collect your bag after your swim.
Can I swim in a team with a group of friends?
Absolutely, in fact we encourage it. The more people who swim together and look out for each other, the safer the event is. If you wish to swim with friends, please make sure that you all enter the same wave.
Will I be able to wear a tow float?
All swimmers will be required to use a tow float and are advised to get used to swimming with one before the event. You can purchase a discounted Swim Secure tow float when you register
How will you ensure that those who want to do solo swims are able to do so safely?
We have a fully approved safety plan that ensures coverage across the full course throughout the event. In addition ALL swimmers will be required to use a tow-float.
Can I swim non-wetsuit?
We have a limited number of non-wetsuit places available for both the Half Marathon and the Full Marathon. This is to minimise the risk to our safety plan. Wetsuits are important for retaining heat and providing buoyancy. If you would like a non-wetsuit place in the full marathon your application will be assessed by the events team for approval.
Non-wetsuit places sell out very quickly, we recommend applying as soon as registration opens.
How many feed stops will there be ?
There will be 3 feed stops for the full Thames Marathon and 2 for the Half Marathon.
What food will be available at the feed stops?
We will provide a bit of everything for this long-distance swim, including bananas, energy bars, energy drinks, water, some chocolate, sweets, and some salty snacks. If you wish to use energy gel, please bring your own in your tow float, so that you know the particular brand that you use will suit you.
How will the start work (full marathon)?
The slower swimmers will set off first. The faster swimmers will set off after with those expecting to finish under 3 and a half hours setting off last. Swimmers will be dropped at the start ‘swim-ready’ and will get off the coach, walk to the start and straight into the water for a rolling start within their wave time.
How should I choose which wave to enter?
The Thames Marathon will be setting off from Henley from 7.30am. Strong swimmers who are seeking a faster time and who expect to complete the course in under 4 hours (approximately equivalent to a sub 27-minute mile pace) should select waves 7-10. If you expect your time to be under 3½ hours, please select wave 10, between 3½ and 4 hours select wave 7, 8 or 9. Other swimmers should select wave 1 – 6 – these are all mixed ability waves. If you wish to swim with a group, please ensure that you all select the same wave.
There will be a cut-off time of six and a half hours for the full marathon, 5 hours for the mid-distance marathon and three and a half hours for the half marathon, where all swimmers will need to be out of the river. If you anticipate that you will take longer than this, please contact [email protected] before entering.
Are there toilets on the course?
There are toilets at Higginson Park. There are a couple of cafes and pubs near the walking route. Please note that once you have left Higginson Park on the coach, there will be no toilets at the start of either the full or half-marathon.
Can supporters walk the route?
The route is walkable, by following The Thames Path. It is also possible to cycle the route, although there are a large number of kissing style gates where you may have to lift your bikes to get through and it may be difficult with tag-alongs.
Supporters that start with their swimmer at Higginson Park can walk upstream until they meet the swimmers, and walk back downstream alongside them. Alternatively they can stay at the event village or go into Marlow for a coffee, and wait for the swimmers to return.
Supporters can be dropped at the start of the full-distance in Henley by friends or family with their swimmer, and walk the full distance of the course, but there is no parking at the start.
Can I talk to fellow swimmers in advance of the event?
Definitely, we have set up Henley Swim Chatter as a facebook forum, where you are able to discuss anything with fellow swimmers from nutrition and training tips to transport to the event on the day.
The actual distance that you swim will depend upon several factors including the start and finish points, the precise course (inside or outside of the bends), how straight you swim (zig zagging even slightly can make a difference across this distance) and the exact location of the exits and re-entries around the locks and weirs. Some of these variables will not be confirmed until much closer to the event.
On average the distance travelled will be around 13km or 5.5km, however this is not ratified
On average the distance travelled will be around 13km or 5.5km, however this is not ratified
To apply for a wetsuit place click Enter on the Wetsuit Category above.
You will be asked to select your wave, please do so based on the following criteria:
Wave 1 - this wave is for slower swimmers, who expect to take longer than 5½ hours to complete the course.
Waves 2-6 - these waves will be mixed ability waves. If you do not consider yourself a racing swimmer, please select one of waves 2 to 6
Wave 7-10 - these waves are ideal for swimmers who are seeking a faster time and who expect to complete the course in under 4 hours (approximately equivalent to a sub 27 minute mile pace). If you expect your time to be under 3½ hours, please select wave 10, between 3½ and 4 hours select wave 7, 8 or 9.
Non-Wetsuit places:
There are a limited number of places open to non-wetsuit swimmers, subject to experience and ability. This is to adhere to our safety plan. Wetsuits are important for retaining heat and providing buoyancy. If you would like a non-wetsuit place your application will be assessed by the events team for approval. Wetsuits for the Thames Marathon can be sleeveless, but must be below the knee.
There will be a cut-off time of 6½ hours for the full distance and 3 hours for the half distance, where all swimmers will need to be out of the river.
Tow Floats will be compulsory for ALL swimmers. There is an opportunity to buy a tow float during the registration process.
You will be asked to select your wave, please do so based on the following criteria:
Wave 1 - this wave is for slower swimmers, who expect to take longer than 5½ hours to complete the course.
Waves 2-6 - these waves will be mixed ability waves. If you do not consider yourself a racing swimmer, please select one of waves 2 to 6
Wave 7-10 - these waves are ideal for swimmers who are seeking a faster time and who expect to complete the course in under 4 hours (approximately equivalent to a sub 27 minute mile pace). If you expect your time to be under 3½ hours, please select wave 10, between 3½ and 4 hours select wave 7, 8 or 9.
Non-Wetsuit places:
There are a limited number of places open to non-wetsuit swimmers, subject to experience and ability. This is to adhere to our safety plan. Wetsuits are important for retaining heat and providing buoyancy. If you would like a non-wetsuit place your application will be assessed by the events team for approval. Wetsuits for the Thames Marathon can be sleeveless, but must be below the knee.
There will be a cut-off time of 6½ hours for the full distance and 3 hours for the half distance, where all swimmers will need to be out of the river.
Tow Floats will be compulsory for ALL swimmers. There is an opportunity to buy a tow float during the registration process.
Organiser's description
CURRENTLY ON EARLY BIRD PRICES!
The Thames Marathon has been previously rated the Top-Rated swim by Racecheck, and has won several gold awards! It has become one of open water swimming's most prestigious and well-known swims, attracting swimmers from all around the world as well as many locally. The swims are split into sections, due to the locks on the river, which make them manageable for many types of swimmer.
The event has several swim options on the same day, taking place on an incredibly stunning stretch of the River Thames between Henley-on-Thames and Marlow.
-The full Thames Marathon - 13km swim - The swim is split into 4 sections. Swimmers will be required to exit the water at the 3 locks (Hambleden, Hurley and Temple ) where drinks and energy snacks will be available.
-The Mid-Distance - 9km - The swim is split into 3 sections. Swimmers will be required to exit the water at the 2 locks (Hurley and Temple) where drinks and energy snacks will be available.
-The Half Marathon - 5.5km - The swim is split into 3 sections. Swimmers will be required to exit the water at the 2 locks (Hurley and Temple) where drinks and energy snacks will be available
-The Thames Marathon Relay - 13km between 3 swimmers - each swimmer will swim a 4/5km section while the other two walk it, finishing all together at the end in Marlow.
The Event Village and Parking is at Higginson Park in Marlow. Swimmers will be transported by coach to the start of each distance and will swim back to Marlow. There is also the option to walk or run to the start of the Half Marathon.
This event is fantastic for spectators/ supporters as the finish is in a central park in the stunning town of Marlow, the Thames path is a lovely walk, and there is an amazing vibe.
The Thames Marathon has been previously rated the Top-Rated swim by Racecheck, and has won several gold awards! It has become one of open water swimming's most prestigious and well-known swims, attracting swimmers from all around the world as well as many locally. The swims are split into sections, due to the locks on the river, which make them manageable for many types of swimmer.
The event has several swim options on the same day, taking place on an incredibly stunning stretch of the River Thames between Henley-on-Thames and Marlow.
-The full Thames Marathon - 13km swim - The swim is split into 4 sections. Swimmers will be required to exit the water at the 3 locks (Hambleden, Hurley and Temple ) where drinks and energy snacks will be available.
-The Mid-Distance - 9km - The swim is split into 3 sections. Swimmers will be required to exit the water at the 2 locks (Hurley and Temple) where drinks and energy snacks will be available.
-The Half Marathon - 5.5km - The swim is split into 3 sections. Swimmers will be required to exit the water at the 2 locks (Hurley and Temple) where drinks and energy snacks will be available
-The Thames Marathon Relay - 13km between 3 swimmers - each swimmer will swim a 4/5km section while the other two walk it, finishing all together at the end in Marlow.
The Event Village and Parking is at Higginson Park in Marlow. Swimmers will be transported by coach to the start of each distance and will swim back to Marlow. There is also the option to walk or run to the start of the Half Marathon.
This event is fantastic for spectators/ supporters as the finish is in a central park in the stunning town of Marlow, the Thames path is a lovely walk, and there is an amazing vibe.
Location
Higginson Park, Pound Lane, Marlow, SL7 2AE, United Kingdom
Thames Marathon Swim
HS
Henley Swim
Henley Swim has a range of open water swimming events, covering distances from 200m to 13km, at different times of day, upstream and downstream, wetsuit and non-wetsuit, from age 8 to 88. We cater for the requirements of everyone from the novice to the experienced swimmer.
On Find a Race
Since
2015
Events
10+
Avg. review
4.8