The Rival Submarines

A mysterious, technologically advanced private submarine eludes naval authorities off a major harbour, baffling experts with an unusual diving suit and unheard-of equipment; Sub-Lieutenant Arnold Hythe is assigned to the surveying vessel Investigator to locate it. The craft undertakes daring acts that spark international alarm and diplomatic accusations, prompting naval mobilization and intensified coastal surveillance. The narrative follows the prolonged hunt, including diving operations, acoustic detection, canal and sea transits, rescues, and shipboard confrontations as rival captains and crews clash. The pursuit resolves through resourceful tactics, captures, and revelations that explain the submarine's methods and end the menace.