Beal joined the U.S. Navy in 1948, first serving aboard the U.S.S. Shenandoah as a gunner's mate. He joined the underwater demolition team, the precursor to the Navy SEALs, in 1955. When the first Navy SEALs team was established in 1962, Beal was the first to volunteer for the elite special operations force. Later, Beal was credited with pulling John Glenn out of the water after his historic spaceflight. Beal became a SEAL instructor, serving until his retirement from the U.S. Navy in 1968.