THAMES MARATHON 2025 - 13km / 9km / 5.5km SWIM

The Thames Marathon is an endurance swim between Henley-on-Thames and Marlow with a choice of 3 distances.

This swim covers one of the most stunning stretches of the River Thames and has become one of open water swimming’s most prestigious marathon swims.

The Thames Marathon swim is approximately 13km and is split into 4 sections. Swimmers will be required to exit the water at the 3 locks (Hambleden, Hurley and Temple).

There is also a 9km option, a 5.5km option and a relay.

Drinks and energy snacks will be available for all swimmers at the locks, home to our famous feed stations!

The event has again received a Gold Racecheck Award in 2024, with a score of 4.8/5 and consistently high review from swimmers.

It is the perfect event for a personal or charity challenge.

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Come swim the Marathon with us in 2025!

You may also like the following events from The Henley Swim:

• This July, 11th July, 03:00 pm, Outdoor Swimmer Henley Swim Festival 2025 in Henley-on-thames
• This July, 26th July, 06:30 pm, Club to Pub 2025 in Henley-on-thames

Also check out other Sports events in Marlow, Nonprofit events in Marlow.