Event Info

Swimmer Info


Swimmers will set off at the following times at the 2018 edition of Swim Serpentine.

1 Half Mile 08:30
2 Para Swimmers One Mile (Invitation Only) 09:00
3 One Mile (Women Only) 09:10
4 One MIle 09:45
5 One Mile 10:15
6 Two Mile 10:45
7 Two Mile 11:45
8 One Mile 12:45
9 One Mile 13:15
10 Two Mile 13:45
11 Two Mile 14:45
12 Two Mile 15:45

Wearing a wetsuit or using a tow-float

Everyone who takes part in the Swim Serpentine events must either wear a full length 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.

Hire a HUUB Wetsuit for Swim Serpentine

If you would like to hire a wetsuit for the event from 220 Triathlon's number one wetsuit brand, look no further than HUUB.

You have the option of two-week hire for £40* or £70* for the entire open water season (*refundable deposit required). If you choose two-week hire, the wetsuit will be shipped for delivery to you by 10 September 2018 and must be returned and received by us before 5 October 2018.

To avoid disappointment, hire wetsuits should be ordered online before the event as we will have very limited stock on the day and cannot guarantee to have your size. Please note that hire wetsuits can NOT be returned on the day of the event.

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.

Final Instructions

A Final Instructions e-magazine will be emailed to all participants at the end of August and will also be available to download on this page.

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.