Leonardo da Vinci sketched a submarine with a concealed underwater hull.
In notes associated with his military engineering, Leonardo described a vessel capable of traveling underwater and attacking enemy ships. The idea is commonly connected with a secret design: accounts say he did not provide complete construction details because he feared the technology could enable destructive naval warfare. The surviving material is not a complete operational blueprint.
Leonardo’s submarine concept belongs to a long history of underwater-boat proposals. It did not have the engines, pressure hull, ballast systems, navigation instruments, or reliable air management required by later submarines. The first documented successful human-powered submarine, David Bushnell’s Turtle, appeared in 1775, more than two centuries after Leonardo’s lifetime.
The concept also differs from Leonardo’s diving suit. A submarine carries its occupants inside a vessel, while a diving suit surrounds an individual in the water. Leonardo explored both possibilities as part of his broader interest in military and mechanical engineering.