The one to book if you are staying in Southampton, Water Mill or Sag Harbor — the studio's own page names those three as who it is for, and it saves the drive east to Wainscott.
boxingHiit · Southampton
Barry's Southampton
The second Hamptons Red Room, and the one nobody has noticed: treadmill-and-floor HIIT on Montauk Highway in Southampton village, a separate seasonal studio from the Wainscott one, with its own hours and its own phone.