Manthos started diving in 1988 and became an instructor in 1995, while he continues up to this day. He is also in charge of the company’s underwater department. During his military service, he served in the underwater operation unit of the Army Special Forces (135th School).
He also participated in large projects such as “The Britannic project’’ (Britannic, Titanic’s sister ship, shank near the greek island of Kea in 1916). In 1997 Manthos Sotiriou and an international diving team, lead by Kevin Gurr, visited and filmed the wreck in about 120m (400 ft) depth. Manthos is an upper level certified diver on recreational diving, rebreathe and technical nitro – trimix.