Mark Spencer joined the Deerfield Academy coaching staff in 2013 and currently serves as the Head Coach of the Boys’ Varsity Swimming & Diving team. During his tenure, the Big Green have strengthened an already storied tradition—combining elite results with a team-first culture that emphasizes camaraderie, resilience, accountability, and joy in the daily grind.
Spencer calls swimming “the ultimate collective sport,” where every heat, split, dive – and swimmer – matters. He blends meticulous technical work with individualized, science-based training—incorporating everything from race-pace analytics to nutritional guidance—while encouraging athletes to find ways each day to elevate their teammates. He credits assistant coach Melanie Onufrieff and diving coach Jason Cook for helping to bring that philosophy to life, and points to the strong collaboration with Deerfield’s girls’ program as “one of our quiet super-powers.”
Since taking over the program, Spencer has helped reestablish Deerfield as a championship contender. The 2023–2024 “Dream Team” broke three school records, won gold in the 200 Medley Relay, scored over 300 points at the Division I NEPSAC Championships, and produced five All-Americans. The 2021–2022 season was similarly notable and has become known as the “30-for-30” Season, as the team posted 30 personal-best swims in 30 finals appearances despite pandemic disruptions and also saw three divers place in the top ten! Since 2016, Deerfield has consistently finished in the top five in New England, claimed nine All-NEPSAC relay titles, and added more than a dozen new marks to the boys’ record board. Graduates have continued their success at the collegiate level, competing at Carnegie Mellon, Colgate, Michigan, Cornell, Boston University, Denison, Bates, the University of Virginia, and other top programs. Two recent alumni even qualified for the U.S. Olympic Trials.
The team trains and competes in the Koch Pool, an eight-lane, 25-yard competition venue with a dedicated diving well that has hosted multiple NEPSAC Championships. Known for its fast water and high-energy deck atmosphere, the Koch Pool has become a fitting stage for Deerfield’s recent swimming and diving successes.
In addition to his coaching duties, Spencer serves as Dean of College Advising and lives on campus in Nims House with his wife, Elizabeth, and their two daughters, Ruthie and Gracie.