The One on the River (Marlow / Henley)
Marlow, United Kingdom · May · Independent (OneRace Events)
Course: 1.5 km (0.9 mi) swim, 37 km (23.0 mi) bike, 10 km (6.2 mi) run. 1,500 m (0.93 mi) river swim, 37 to 40 km (23 to 25 mi) bike, 10 km (6.2 mi) run
Why people love it
- Marlow race: river Thames swim with personal safety kayaks; reviewers felt secure on their first open-water swim.
- Sprint is 750 m (0.47 mi) swim, 24 km (14.9 mi) bike, 5 km (3.1 mi) run.
- Run on the flat Thames path from Higginson Park, 5 km (3.1 mi) or 10 km (6.2 mi).
- Small, low-key field of about 1,000 across all events.
- Park setting beside Marlow town and its suspension bridge.
Watch out for
- All reviews found are for Marlow. Nobody has written about the Henley date yet.
- Roads are open to traffic; reviewers report a hilly bike and potholes.
- In 2024 the triathlon swim was cancelled for water quality and became a duathlon.
- One 2023 reviewer measured the standard run about 700 m (0.43 mi) short.
- Dates vary by listing: check the organiser before entering.
Race
How racers feel about it, how well it is run, and how it treats a first timer. Counts for 30% of the overall score.
Toughness: Tough
- Racer satisfactionLoved4.1
Racecheck shows 29 ratings at 4.6 and reviews at 4.5, but only Marlow is covered and several reviews are for other events. · Medium confidence
- OrganizationWell run3.8
Reviewers found pre-race info unclear, the 2024 swim was cancelled for water quality, and one run measured short. · Medium confidence
- First timer friendlyDoable3.0
1,500 m (0.93 mi) river swim and hilly open roads need prep. · Low confidence
Course traits, not part of the score
- PR potentialAverage2.7
Longer hilly 37 to 40 km (23 to 25 mi) bike on open roads. · Low confidence
Swim
Wetsuit odds, water temperature, calm, and the experience of the start. Counts for 16% of the overall score.
- Wetsuit legalUsually4.0
Triathlon England follows World Triathlon, which bans wetsuits above 24.6 °C (76.3 °F); the Thames in late May is usually below that. · Low confidence
- Water temperatureAcceptable3.2
River temperature not published; May Thames is normally 14 to 18 °C (57 to 64 °F), estimated. · Low confidence
- Calm waterMostly calm4.0
The Thames at Marlow flows gently in late spring and summer; reviewers report no current or chop problems. · Low confidence
- Swim easeEasy3.6
1,500 m (0.93 mi) in a river with flow. · Low confidence
- Swim experienceGreat3.6
A first-time open-water swimmer loved it, but the water quality led to a 2024 duathlon swap. · Medium confidence
- Swim supportGood4.2
Reviewers had personal safety kayaks and felt secure on the river; waves reduce crowding. · Medium confidence
Bike
Road surface, closures, scenery and wind. Counts for 18% of the overall score.
- Road surfaceMixed2.7
Reviewer asks marshals to mark potholes. · Low confidence
- Road closuresMostly open1.8
Roads were not closed to traffic. · Medium confidence
- Bike sceneryBeautiful3.8
Thames valley and Chilterns countryside. · Low confidence
- WindSome wind3.2
No wind reports; sheltered river valley. · Low confidence
Course traits, not part of the score
- Bike speedAverage3.0
Hilly open roads. · Low confidence
- Bike flatnessHilly2.4
Hilly over 37 to 40 km (23 to 25 mi), no elevation published. · Low confidence
- Bike simplicitySome technical parts3.3
No technical issues reported. · Low confidence
Run
Crowds, aid stations, conditions underfoot and scenery. Counts for 13% of the overall score.
- Crowd supportDecent3.4
DJ and local support mentioned, but a small field. · Low confidence
- Aid stationsStandard3.0
Reviewer said feed stations offered only water. · Low confidence
- Run sceneryBeautiful4.2
Thames path through Marlow. · Medium confidence
- Run conditionsEasy3.7
Flat path over 10 km (6.2 mi). · Low confidence
Course traits, not part of the score
- Run flatnessMostly flat4.4
Flat Thames path. · Medium confidence
Conditions
Air temperature, how predictable the weather is, setting, and spectating. Counts for 13% of the overall score.
- Air temperaturePleasant3.6
Late spring and summer highs about 16 to 22 °C (61 to 72 °F). · Low confidence
- Weather reliabilityVariable3.0
English weather; no cancellations reported. · Low confidence
- Venue beautyLovely4.3
Higginson Park beside the Thames and Marlow suspension bridge. · Medium confidence
- Spectator friendlyEasy3.8
Park venue by the river with food and drink. · Low confidence
Course traits, not part of the score
- Low altitudeSea level4.9
About 35 m (115 ft) above sea level. · Medium confidence
Stay and travel
Hotels, walkability, getting there, and the town around the race. Counts for 10% of the overall score.
- Hotel availabilityGood3.6
Limited in Marlow; Henley and Maidenhead nearby. · Low confidence
- Hotel valueNormal2.8
Pricey Thames Valley hotels. · Low confidence
- WalkabilityWalkable4.0
Event is held in the park next to town. · Low confidence
- Travel easeEasy3.9
About 35 km (22 mi) from Heathrow; rail via Bourne End or Maidenhead. · Medium confidence
- LogisticsSome complexity3.4
One venue; pre-race info criticised by one reviewer. · Low confidence
- Town and foodGood4.2
Marlow has a good high street and pubs. · Medium confidence
Key facts
- Location
- Marlow, Buckinghamshire, United Kingdom
- Typical month
- May
- Latest or next date
- 30 May 2027
- Organiser
- Independent (OneRace Events)
- Field size
- About 1,000 athletes
- Distances (non-standard)
- 1.5 km (0.9 mi) swim, 37 km (23.0 mi) bike, 10 km (6.2 mi) run
- Swim venue
- River Thames at Higginson Park, Marlow (river)
- Wetsuit
- Legal unless the water is too warm
- Swim start
- waves
- Swim laps
- 1
- Air temperature
- 12–22 °C (54–72 °F)
- Altitude
- 35 m (115 ft)
- Nearest airport
- London Heathrow (LHR), 35 km (22 mi) away
- Where to stay
- Marlow town centre
- Booking
- Day-trip race; Marlow hotels are limited and dear on race weekends.
What racers and reviewers say
- RacecheckRaced 2023 · aggregator · Positive
Ten written reviews from 2023 and 2024, of which six are for sprint or standard triathlon and the rest for duathlon, aquabike, swim or middle distance. They average 4.5 out of 5, with 29 ratings overall at 4.6. Reviewers like the setting, safety kayaks and friendly low-key feel; criticisms are a small field, pre-race info, potholes, a 2024 swim cancelled for water quality, and a short run.
Raced The One on the River (Marlow / Henley)? Your notes on the course, conditions and logistics help the next athlete decide.
Sources
Pages we used for facts and ratings. See how we rate.
Training for The One on the River (Marlow / Henley)? Moku Coach builds your plan around race day.