Model of submersible 'Turtle', 1776.
© Science Museum / Science & Society Picture Library
Model of Turtle prior to conservation. David Bushnell designed the Turtle which was the first American submarine, built in 1776. The Turtle was powered by a hand driven propeller and would normally float with approximately six inches of exposed surface. It was used during the American War of Independence, in order to break the British naval blockade of New York harbour.