June 10, 2018. Casco, Maine. The Sebago Lake Triathlon is a fun, adult triathlon that takes place at Point Sebago Resort in scenic Casco, Maine. With a beach, playground, and snack bar at the venue, the Sebago Lake Triathlon is a great event for the whole family. Offering both Sprint and Olympic distances (Sprint race is part of the New England Triathlon Tour), the race has a protected swim on Sebago Lake, a challenging bike course on country roads, and a run through Point Sebago Resort. A great post-race barbeque!