Event Info

Swimmer Info

Wearing a wetsuit or using a tow-float

Everyone who takes part in the Swim Serpentine events must either wear a wetsuit or use a tow-float for safety reasons.

If the temperature of the water in the Serpentine is 15°C or above, wetsuits are optional at Swim Serpentine. If you choose not to wear a wetsuit, you must use a tow-float.

If the water temperature is under 15°C, wetsuits are compulsory.

Water temperature guidelines

The weather in the weeks leading up to the swim will determine the water temperature.

Below is some important information on the water temperature and how it could affect your swim.

15-29°C half mile Optional 1hr 10 mins
15-29°C 1 mile Optional 1hr 40 mins
15-29°C 2 miles Optional 2hr 50 mins
13.5-14.9°C half mile Compulsory 1hr
13.5-14.9°C 1 mile Compulsory 1hr 10mins
13.5-14.9°C 2 miles Compulsory 1hr 30 mins

*Maximum time in water times have been reached based on guidance from our medical & water safety team, in line with governing body guidelines and medical evidence around swimming in water of 14°C and below. These times will be used by our team on-site to monitor swimmers still in the water, and to enable them to assess the welfare of any swimmer still in the water, exceeding these times. Swimmers may be permitted to continue swimming in excess of the maximum time in the water, providing they are assessed fit to do so by our safety team. Any swimmers showing signs of hypothermia will be asked to exit the water for their own safety and well-being.

Water temperature and reduced distance (only applicable when water temperature is under 13.5°C)
13.4°C & under half mile Compulsory N/A 45 mins
13.4°C & under 1 mile Compulsory 1 mile
(800m option if slower than 45 min per mile pace)
45 mins
13.4°C & under 2 mile Compulsory 1 mile
(800m option if slower than 45 min per mile pace)
45 mins

Keep an eye on the Swim Serpentine Facebook page for up-to-date water temp in the build up to the event.

Wetsuits, swimwear and swim accessories are available to hire or purchase on the day from our official partners, HUUB.

The cost of hire is £40 plus a refundable deposit of £159.99. These will be strictly on a first come first serve basis, so please get there early to avoid disappointment. 

After your swim the hire wetsuit must be taken home, rinsed clean and dried out. HUUB can't accept them back on the stand so make sure you receive a returns form when you hire a wetsuit. Once the wetsuit is returned, you will be refunded the £159.99 deposit.

Tow-floats will be available to hire or buy on the day from our partner, Swim Secure. The price to purchase is £20. Hire of used tow-floats costs £10, with £5 refundable on return.

Final Instructions

A Final Instructions booklet will be mailed out to all participants in Swim Serpentine. A condensed version of these instructions will also be available to download.

Medical Information

We are happy for people even with serious medical conditions to swim, but only with their GP’s and/or specialist’s agreement. If this applies to you, please send us details of your condition and the treatment with your name and swimming number. Address the envelope to Medical Director, mark it ‘confidential’ and send it to:

Swim Serpentine
London Marathon Events Ltd
P O Box 1234
London SE1 8RZ

We cannot give individual swimmers advice but are happy to advise your GP.

Swimmer Safety

The Swim Serpentine course will be clearly marked by large buoys, and a water safety team is on hand to assist any swimmers on the day if needed. All swimmers should complete their chosen distance in full while training in a pool.

Swimmers should also practise swimming in the open water before the event.

Your swim hat

We have sent you a silicone swim hat for the event. You MUST wear this hat as it displays your start wave colour. If you have a favourite swim hat that you usually swim in, you can wear this underneath your Swim Serpentine swim hat – but please take care not to overheat if it is warm on the day of the race.

Your time

Finish times from the 2017 edition of Swim Serpentine are now available to view.

Age Group Prizes

The mass participation events are not races, with the main focus on fun. However, specially designed age group medals will be mailed out post-event to the top three male and female finishers in the following age group categories:

One and Two-Mile Swims: 16-24 years old, then 10-year age bands starting at 25 years old.

The Half-Mile Swim is a fun event, although the top three male and female finishers in the 12/13 and 14/15 age categories, who are unable to enter the longer events, will also be awarded medals.


If you have a specific question or issue, check out the FAQs here.