The Boston Triathlon
Boston (South Boston), United States · August · Boston Triathlon (Mike O'Neil)
Course: 0.8 km (0.5 mi) swim, 18.5 km (11.5 mi) bike, 5 km (3.1 mi) run. 0.5 mi (0.8 km) swim, 11.47 mi (18.5 km) bike, 3.1 mi (5 km) run; some press items list 750 m / 17.5 km / 5.5 km.
Why people love it
- Flat bike on car-free closed roads, with four lanes shut
- Beach swim with the Boston skyline behind: Olympic 0.9 mi (1.45 km), sprint 0.5 mi (0.8 km)
- Compact race village; Logan Airport is about 8 km (5 mi) away
- Free swim clinic, relays and a sprint that suits first-timers
- Kids Day the day before
Watch out for
- Swim can be choppy and was cancelled in 2018
- Each 5.7 mi (9.2 km) bike loop has 3 U-turns and 2 no-passing zones
- Olympic bike is 22.9 mi (36.9 km), short of the 40 km (24.9 mi) standard
- Long T1 over sand; later waves have waited up to 75 minutes on the beach
- Late-August sun with little run shade; entry about $190 sprint, $240 Olympic
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: Moderate
- Racer satisfactionLoved3.8
Race reports and forum posts from 2016 to 2019 call it a solid, well-run city race. Gripes: bike turns, choppy or cancelled swims, price. · Medium confidence
- OrganizationWell run3.9
Fast packet pickup, volunteers policing passing and free photos; 'very well organized' per a 2016 to 2017 racer. One swim was cancelled in 2018. · Medium confidence
- First timer friendlyFriendly4.0
0.5 mi (0.8 km) swim, 11.47 mi (18.5 km) flat closed bike, 3.1 mi (5 km) run; called a good first race. · Low confidence
Course traits, not part of the score
- PR potentialAverage3.3
Flat but turns and crowding on the 11.47 mi (18.5 km) bike. · Low confidence
Swim
Wetsuit odds, water temperature, calm, and the experience of the start. Counts for 16% of the overall score.
- Wetsuit legalUsually3.5
Low 70s F (21-23 °C (70–73 °F)) per the 2026 guide listing, within USA Triathlon limit of 25.6 °C (78 °F); wetsuits recommended. · Low confidence
- Water temperatureComfortable3.9
About 21-23 °C (70-73 °F) in late August; city harbour water, clean per the director. · Low confidence
- Calm waterSome chop2.8
Chop in 2017, calm in some years and cancelled in 2018; exposed Dorchester Bay beach. · Medium confidence
- Swim easeEasy3.5
0.5 mi (0.8 km) in a variable bay. · Low confidence
- Swim experienceFine3.4
City beach swim with the skyline behind; organised waves; but long waits and variable chop. · Low confidence
- Swim supportGood3.8
Wave starts, bright caps, a free swim clinic and a plan to shorten or cancel the swim when it is rough. · Low confidence
Bike
Road surface, closures, scenery and wind. Counts for 18% of the overall score.
- Road surfaceGood3.5
Wide city roads; surface not discussed in the sources. · Low confidence
- Road closuresFully closed4.8
Car-free closed roads with four lanes shut per organiser and posters; volunteers police passing. · High confidence
- Bike sceneryBeautiful3.7
Waterfront and harbour views along William Day Boulevard; flat urban loops. · Low confidence
- WindSome wind2.9
Exposed harbour front; a poster expects a headwind for about half of each loop. · Low confidence
Course traits, not part of the score
- Bike speedFast3.5
Flat, closed; many turns. · Low confidence
- Bike flatnessPancake flat4.6
Likely under 15 m (50 ft) of climbing over 18.5 km (11.5 mi). · Medium confidence
- Bike simplicitySome technical parts2.6
Three 180-degree turns per loop (2019, 2018 poster) and about 14 slowdowns; chaotic when crowded. · Medium confidence
Run
Crowds, aid stations, conditions underfoot and scenery. Counts for 13% of the overall score.
- Crowd supportStrong3.8
Spectators cheered the 2019 run, with free spectator access in a city setting. One poster found the sidewalk run boring. · Low confidence
- Aid stationsGood3.6
One or two water stations per run loop and portable toilets that a 2017 racer found unannounced. No major complaints. · Low confidence
- Run sceneryBeautiful3.7
Skyline and harbour views per organiser; a poster called it a boring sidewalk route. · Low confidence
- Run conditionsEasy3.6
Single circuit through Moakley Park. · Low confidence
Course traits, not part of the score
- Run flatnessFlat4.6
Estimate under 10 m (33 ft) over 5 km (3.1 mi). · Low confidence
Conditions
Air temperature, how predictable the weather is, setting, and spectating. Counts for 13% of the overall score.
- Air temperatureWarm or cool3.4
Late-August Boston is likely 20 to 29 °C (68 to 84 °F) and humid; a 2019 racer faded in the heat. · Low confidence
- Weather reliabilityVariable3.2
Harbour swim variability and a cancelled swim in 2018; otherwise summer mornings. · Medium confidence
- Venue beautyLovely4.0
Carson Beach with the Boston skyline and a city race village. · Medium confidence
- Spectator friendlyEasy4.3
Free spectating, compact village and multiple loops; Kids Day Saturday. · Medium confidence
Course traits, not part of the score
- Low altitudeSea level5.0
Sea level, about 3 m (10 ft). · High confidence
Stay and travel
Hotels, walkability, getting there, and the town around the race. Counts for 10% of the overall score.
- Hotel availabilityBook early3.0
Boston in August is busy; many rooms but pricey. · Low confidence
- Hotel valuePricey1.9
Major city race weekend; high August rates. · Medium confidence
- WalkabilityWalkable3.5
Red Line access and a compact race village, though many racers drive 15 to 20 minutes from the suburbs. · Low confidence
- Travel easeVery easy4.7
Boston Logan Airport is about 8 km (5 mi) from the venue and the Red Line is nearby. · High confidence
- LogisticsSimple3.6
One venue, Saturday bike racking and quick packet pickup, but a long T1 run over sand and later waves waiting up to 75 minutes. · Medium confidence
- Town and foodGreat4.5
South Boston, Seaport and downtown restaurants are close. · Medium confidence
Key facts
- Location
- Boston (South Boston), Massachusetts, United States
- Typical month
- August
- Latest or next date
- 23 August 2026
- Organiser
- Boston Triathlon (Mike O'Neil)
- Field size
- About 2,000 athletes
- Entry fee
- About $190
- First held
- 2009
- Distances (non-standard)
- 0.8 km (0.5 mi) swim, 18.5 km (11.5 mi) bike, 5 km (3.1 mi) run
- Swim venue
- Carson Beach, Dorchester Bay, by the DCR McCormack Bathhouse (bay)
- Water temperature
- 21–23 °C (70–73 °F)
- Wetsuit
- Recommended by organiser; USA Triathlon rules (legal to 25.6 C / 78 F)
- Swim start
- wave start from the beach, clockwise course (sprint waves later; novice waves last)
- Swim laps
- 1
- Bike laps
- 2
- Run laps
- 1
- Run shade
- Little
- Air temperature
- 20–29 °C (68–84 °F)
- Humidity
- Moderate to high
- Altitude
- 3 m (10 ft)
- Nearest airport
- Boston Logan (BOS), 8 km (5 mi) away
- Where to stay
- South Boston, Seaport, Dorchester, Red Line suburbs
- Booking
- Boston August hotel prices are high; book months ahead or stay in suburbs near the Red Line.
What racers and reviewers say
- Snacking in Sneakers: 9 reasons to race the Boston TriathlonRaced 2017 · article · Positive
Sponsored guide promoting flat courses, a car-free bike, relay options and a post-race party; useful on beginner friendliness but promotional.
- Slowtwitch: The Man Behind the Boston Triathlonarticle · Positive
Profile of the race director: separate bike and run roads after expanded permits made the course safer and faster, calm clean water at Carson Beach, 65% Massachusetts entrants and a field that said it felt like a world championship without the stress.
“felt like a world championship”
- Boston Globe: Boston Triathlon 2025 resultsRaced 2025 · article · Positive
Results recap: elite Olympic winners 1:52:20 and 1:56:43, sprint winners 1:00:05 and 1:03:48, a field packed with locals, no problems reported.
- WHDH: Thousands gather at Carson Beach for the Boston TriathlonRaced 2023 · article · Positive
TV news item from 27 Aug 2023: first waves in the water by 7:30 am, with the race director stressing inclusiveness.
Raced The Boston Triathlon? 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 Boston Triathlon? Moku Coach builds your plan around race day.