Event Info

Swimmers enter the water at Swim Serpentine

Swimmer Info

Final Instructions

Final Instructions for swimmers will be e-mailed to all participants ahead of the 2019 event and are available to view below.


Swimmers will set off at the following times at the 2019 Children with Cancer UK Swim Serpentine. Please note times are subject to change.

Half Mile 08:30
One Mile (Women Only) 09:00
Two Mile 09:35
Two Mile 10:30
One Mile 11:25
Two Mile 11:55
Two Mile 12:50
One Mile 13:45
Two Mile 14:15
Two Mile 15:10
One Mile 16:05
One Mile 16:35

The course

To view The Children with Cancer UK Swim Serpentine course for 2019, click the link below.

2019 Children with Cancer UK Swim Serpentine course map

Swimmers with Disabilities

We welcome para swimmers and swimmers with a disability at Children with Cancer UK Swim Serpentine. There is not a dedicated para swimmers wave so you will be able to choose which wave you enter when you sign up. If you require help or support on event day, please contact disability@londonmarathonevents.co.uk

Swimmer celebrates at Swim Serpentine

The event offers a safe, inclusive environment for swimmers of all abilities, who we look forward to welcoming to the Serpentine in September. 

Participants with a disability can register to receive a London Classics medal if they complete the London Marathon, the Prudential RideLondon-Surrey 46 and the two-mile distance at the Children with Cancer UK Swim Serpentine.

Your Swim Pack

All participants will receive a Swim Pack before the event.

Your Swim Pack containing everything you need for the day will be posted to you.

It contains the following:

  • Swim hat matching your wave colour
  • Timing tag* and ankle strap
  • Wristband displaying your swim number, wave details and colour, and your baggage code of letters and numbers
  • Kitbag with self-adhesive sticker matching the baggage code on your wristband

Please note: your swim number and your baggage code are different and are both unique to you.

If you have not received your Swim Pack by Monday 16 September, please email replacementpacks@londonmarathonevents.co.uk with your full name and date of birth and we will arrange a replacement pack to be prepared for you.

London Classics Finishers

London Classics medal

If you are set to complete the London Classics at Children with Cancer UK Swim Serpentine, you will pick up your London Classics medal from the collection point in the Finish Area after your swim.

Wearing a wetsuit or using a tow-float

Everyone who takes part in Children with Cancer UK 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 Children with Cancer UK 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 Children with Cancer UK Swim Serpentine Facebook page for up-to-date water temp in the build up to the event.

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 to helpdesk@londonmarathonevents.co.uk

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

Swimmer Safety

The Children with Cancer UK 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 time

Finish times from the 2018 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.