- Sun 21 Jun 2026
08:00
Age 15 & over on 31 Dec 2026
£62
- 750 m lake swimming
- 20 km road cycling + 158 ft ascent

Event overview
Brought to you by the largest multisports organiser in the UK.
No matter if you are an experienced triathlete looking for a super-fast course to post a Sprint or Standard PB, or a beginner looking for a friendly event to tackle your first triathlon, Stewartby is perfect for you.
You will be treated to a dip in the beautiful lake waters, followed by a very fast, flat, lapped road bike course (probably the fastest bike leg in the country!)
For those completing the aquabike your race will stop at the entrance back in to transition and you'll head off to the finish arch to pick up your well-earned medal. For those competing in the triathlon, you will have a scenic, traffic-free run on flat paths alongside the lake in Marston Vale Country Park.
Highlights
- Beautiful open-water swim in Stewartby Lake
- Super-fast, flat and fully lapped bike course
- Scenic, traffic-free run through Marston Vale Country Park
- Professional event commentary and experienced marshals
- FREE event photos, snacks and finish-line goodies
- Custom-designed finisher medal and friendly atmosphere
This event is part of ATW Stewartby Lake Triathlon & Aquabike.
Event photos
Event details
- Average fitness
- Event village
- Newcomers
- Spectators
- Swim hat required
- Teams
- Wetsuit advised
- Wetsuit not allowed if too hot
- Wetsuit required if too cold
- Distance markers
- Flat
- Marshals
- Traffic free
- GPX available
GPX route
The route is displayed on the map above.
Map



- Changing facilities
- Paid parking
- Park
- Toilets
- Goody bag
- Medal
- Race photo
Included
- Custom designed medal
- Free event photos
- Finish line snacks and goodies
Optional extras
- ICE Band - £22.94
- Personalised Medal Insert - £9
You will need
If you are not a member of British Triathlon already, you will need:
- British Triathlon Federation Race Pass - £8
Superb event and well organised by ATW. Great course with wonderful support. As always a very well run event with a nice bit of bling at the end. Nathan
Great event. Mainly flat so great for a quick time. Also laps so never too far from transition / water stations etc. Great atmosphere and great support. Well organised. Lucy W
First ever Triathlon and really impressed. Lovely setting with a mostly flat course for running and cycling, the organisers and marshals were friendly, encouraging and helpful. Very well organised, kept you at ease whilst also motivated. May be my first but definitely won't be my last triathlon with them. Mark W
Perfect for a PB or first time. Really well organised and laid out to make transition really straightforward. Plenty of space for families or spectators with great views in a lush countryside setting. Highly recommend. Dan G
This is a great race. The lake is a lovely venue and I enjoyed the swim. The bike course is made for PBs, being flat and fast. The run is beautiful - it's around the edge if the lake on a gravel path. Ben R
Reviews thanks to Racecheck
- Plastic bottle free
- Recycling
- Sustainability policy
Here are the ways this event cares for the environment:
Summary
- Recycling bins
- Recycling gets separated from general waste
- Finish line water bottles made from recycled material
- Refill taps are provided so participants can bring their own bottle and fill up during the event
- The choice of paper cups at water stations
- Signage including course marking attached with reusable garden wire instead of plastic cable ties
- 'Dynamic bib assignment’ removes the need for envelopes, sticker labels and excess waste
- Bike racking is provided to promote cycling to the events
- Age 15 & over on 31 Dec 2026
- Entries open
- Enter online
- Event merch available
Entry fees
Early bird entry fee
£62.00
Other races at event
- Sun 21 Jun 2026
- #1 of 0
08:00
Age 15 & over
£73-£94
- 750 m lake swimming
- 20 km road cycling + 158 ft ascent
- 5 km road running + 52 ft ascent
- Sun 21 Jun 2026
- #2 of 0
08:00
Age 17 & over
£94-£115
- 1500 m lake swimming
- 37 km road cycling + 316 ft ascent
- 10 km road running + 104 ft ascent
- Sun 21 Jun 2026
- #4 of 0
08:00
Age 17 & over
£84
- 1500 m lake swimming
- 37 km road cycling + 316 ft ascent
