Race Details

Distance: 1 mile
Date: June 15, 2024. Rain date the following day (June 16)
Start: 8am
Check-in: 6:45am – 7:20am
Location: River Dock (near Arthur Fiedler head statue by the Hatch Shell on Esplanade)
Race Policies: Be sure to read our Race Policies page.

Description: One-mile loop course between Harvard and Longfellow Bridge. Water start.  Please see maps.

Registration and Fees: The fee is $45 until April 30, $55 until May 31, and $65 until June 17 at noon when registration closes.  Sign up early to save on fees!  USMS membership is a requirement and a one-day membership can be purchased as part of the registration process for $15.

Participant Cap: 220 swimmers. The swim typically sells out, so sign up early!

Important Details

  • This swim is not for novices; it is for experienced open-water swimmers only. At a minimum you should be able to swim one mile comfortably in under 40 minutes.
  • Only pre-registered swimmers are allowed to compete.
  • Water temperature: Has historically been 70 degrees or above but can vary based on spring weather patterns.
  • Wetsuits are allowed, unless the water temperature exceeds 78 degrees (per USMS rule).
  • Other assistive devices, including masks, fins, snorkels, and paddles are not allowed.
  • Swimmers are not permitted to wear headphones during the race.
  • USMS membership is required. Day-long membership is $15 and can be purchased as part of the online registration.
  • Age requirement: 18 years minimum
  • Kayakers will provide support during the race
  • Fluorescent swim caps will be provided and must be worn for safety reasons
  • Mandatory Athlete check-in from 6:45am to 7:20am, please bring a photo ID.
  • Pre-race announcement at 7:40am
  • Start 8am
  • Bag-check available


  • This swim is not for novices; this event is for experienced open-water swimmers only. To participate, you should be able to swim one mile comfortably in 40 minutes or less.
  • The race director reserves the right to pull swimmers from the water who cannot complete the course in the allowed time.  This is for safety reasons, as boat traffic must resume along the river immediately following our event.
  • The race is dependent on weather conditions and may be canceled under adverse conditions. Swimmers may encounter random jetsam and flotsam in the river.


  • In the event of heavy or prolonged rainfall, the swim might be canceled. In that case, we will send out an e-mail the day before the race and have a notice on this website.


  • In addition to this page be sure to read our Race Policies page.


  • Awards, awesome t-shirts and post-race refreshments
  • Bragging rights for having swam a mile in the Charles River!


We suggest you arrive by public transportation, biking or walking. The closest MBTA station is the Charles/MGH station on the Red Line or Arlington or Copley Station on the Green Line. Take the Arthur Fiedler footbridge or the Charles/MGH footbridge. Pay parking is available at the Boston Common garage.