While training in the school's pool, Maierson lost consciousness. Medical personnel was present during the training and tried to revive him. Maierson was transported to the Lower Keys Medical Center, where he was later pronounced dead.
The Army has begun an investigation into the incident.
Maierson, a native of Littleton, Colorado, volunteered for military service and entered the Army in September 2003 as a Special Forces Trainee. He earned the coveted "Green Beret" in April 2008.
Maierson is survived by his mother Rose, and Father, Mark Maierson, of Littleton, Colo.