For a quarter-century, this Marlborough staple has been helping triathletes build their way up to longer distances with both Sprint and Super Sprint distances to match your experience level. The Sprint challenge includes a 600-yard swim in the lake, a 2-loop hilly bike ride, and a 5K run along the shore with support at town hall, while the Super Sprint offers an easier entry point with a 200-yard swim, one bike loop of 5.5 miles, and a 1.7-mile run. You can register online for $45 (Sprint) or $35 (Super Sprint), or pay $60/$45 on race day, with relay and aqua/bike options available, gender-based wave starts, and first-come-first-serve bike parking—just note the 6:15pm start time and 4pm online registration cutoff.