New 5.5km half marathon distance added to Thames Marathon

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As part of the 2021 Thames Marathon on 15 August, Henley Swim have announced that they are introducing a new half marathon distance.

Unlike marathon foot races, which have a defined distance, marathon swims can cover any distance of 10km and above. The new shorter distance is approximately 5.5km, and will be called the Thames Half Marathon.

The event is being tested in 2021 with a limited number of places. Swimmers will join in with the full distance swimmers above Hurley, and complete the rest of the course with them. They will finish with the full marathon distance swimmers at the event finish in Higginson Park, Marlow.

To get to the start of the Thames Half Marathon swimmers will have two options: Either walk/run the 6km to the start (this is just for fun, run times will not be recorded), or be transported by coach for a small additional fee. There is no vehicle access to the Half Marathon start, and swimmers cannot be dropped off by family or friends. The swim is split into three sections. Swimmers will be required to exit the water at the two locks (Hurley at 2km and Temple at 3.8km) 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.

Registration will open for the Thames Half Marathon on WEDNESDAY 28th APRIL AT 7PM and demand is expected to be high.

More information can be found at

01 Cover May

Issue 49 May 2021

  • How weather can affect your swim
  • How to train for your first open water mile
  • Where to swim in the Lake District
  • How pioneer women swimmers not only took on men in the open water but also campaigned for the vote
  • Training sessions to ease you back into the pool

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