Open Water Swimming at Herts Young Mariners Base
Difficulty
easy
Duration
1–2 hours
Fitness Level
Swimmers should have a basic level of cardiovascular fitness and comfort in open water.
Overview
Join the Mariners Mile Swim on September 27, 2025, for a scenic and supportive open water challenge in Hertfordshire’s Lea Valley. Perfect for swimmers of all levels, this event combines nature, sport, and community in a memorable way.
Mariners Mile Swim Event
14+
Select participants and date
About This Adventure
Join the Mariners Mile Open Water Swim on September 27, 2025, at HYMB in Cheshunt, Hertfordshire. With distances for all skill levels, participants aged 14 and over can enjoy a scenic swim in the beautiful Lea Valley. Each swimmer receives a medal, and a portion of fees supports Cancer Research UK.
27th September 2025 Start time: 1 pm
HYMB is running its Mariners Mile Open Water Swim event. HYMB is situated within the Lea Valley at Cheshunt, Hertfordshire. There is a distance for all. Open to 14 years and over. 500m loop (main lake) Half-mile Course (both lakes) 1 & 2 plus miles Loop (both Lakes) Price £25 + booking fee Each competitor will receive a Mariner's Mile medal and swim hat.
10% of the entry fee will be donated to Cancer Research UK
Adventure Tips
Wear appropriate swim gear
Ensure your wetsuit or swimwear is suitable for cool water temperatures and comfortable for a prolonged swim.
Hydrate beforehand
Drink plenty of water before the race to stay hydrated during the swim.
Arrive early
Give yourself plenty of time for warm-up, registration, and acclimating to the water.
Check water conditions
Be aware of weather and water temperature on race day to adjust gear accordingly.
Local Insights
Wildlife
- Kingfisher
- Otters
History
Lea Valley has been a vital waterway for centuries, historically supporting trade and recreation, now serving as a popular open water swimming spot.
Conservation
HYMB emphasizes sustainable practices, such as river clean-up initiatives and eco-friendly event management, to protect this natural resource.
Select participants and date
Adventure Hotspots in London
Frequently Asked Questions
Recommended Gear
Wetsuit
A wetsuit helps maintain body temperature and provides buoyancy in open water.
fall specific
Swim cap
A swim cap reduces water resistance and keeps hair out of your face.
Goggles
Goggles protect your eyes and improve visibility underwater.
Towel
A towel is handy for drying off and warming up post-swim.