Thames Marathon 2023

Sunday 13th August 2023

A future version of this event is now available here Thames Marathon 2024 on Sun 11 Aug 2024
Event Details

The Thames Marathon is an endurance swim between Henley-on-Thames and Marlow. It covers a beautiful stretch of the Thames and has become one of open water swimming's most prestigious marathon swims.

The Event Village and Parking will be in Marlow, swimmers will be transported by coach to the full or half distance start, and will swim back to Marlow. There is also the option to walk or run to the start of the half-marathon. 

This year we will be offering a choice of two distances:
THAMES HALF MARATHON – Approximately 5.5km including stops 

The Thames Half Marathon is a 5.5km endurance swim finishing in Marlow. All swimmers will have the option to either walk/run to the Half Marathon start (this is just for fun, run times will not be recorded) or to be transported by coach for a small additional fee. The swim is split into 3 sections. Swimmers will be required to exit the water at the 2 locks (Hurley at 1.5km and Temple at 3.2km) where drinks and energy snacks will be available.

Just like the full distance, non-wetsuit places will be limited, but they will not need to be approved. Once the non-wetsuit places are full this will show on the entry system, and only wetsuit places will be available. 
THAMES MARATHON – Approximately 13km including stops 

The swim is split into 4 sections. Swimmers will be required to exit the water at the 3 locks (Hambleden at 3.8km, Hurley at 9km and Temple at 10.7km) where drinks and energy snacks will be available. 

Wetsuit places:

To apply for a wetsuit place click Enter on the Wetsuit Category below. 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 3½ 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.

Charity Places: 


We are pleased to be working with Macmillan Cancer Support as our Official Charity Partner.  Macmillan aim to help everyone with cancer live life as fully as they can, by providing physical, financial and emotional support. 

If you would like to use your swim to raise money for another charity of your choice, please enter using the OWN PLACE discounted rate below. 

Entry Options - Age 18 & over on Sun 13 Aug 2023
Entries closed
There are no options available at this time please check back later

Refund Policy

Please carefully read clause 5 (cancellation by you) and clause 6 (cancellation by the organisers) of our terms and conditions

Sun 13 Aug 2023 at 07:00
Contact Info
Henley Swim
01491 577922
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Post Code : SL7 2AE