Updated

A 116-year-old experimental submarine originally built for the U.S. Navy was located at the bottom of the Long Island Sound off the coast of Old Saybrook, Connecticut, on Sunday. 

Simon Lake, a naval architect who built the first submarine to operate in the open sea in the 1890s, designed the 92-foot-long Defender as part of a competition for a Navy contract in 1907. 

Former President Theodore Roosevelt had allotted $3,000,000 for submarines, pitting Lake against other designers who were competing for the contracts. 

The Defender, which was originally named the Lake, lost the competition but was later retrofitted for salvage operations and mine clearance work. Lake had a "pet concept of diver operations from a submerged submarine," according to Naval history website NavSource Online. 

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After failing to find a place in the Navy, the Army Corps of Engineers eventually "scuttled" the submarine in 1946 somewhere in the Long Island Sound. 

Richard Simon, a commercial diver from Coventry, Connecticut, set out to find the lost submarine, poring over sonar and underwater mapping surveys until he located an object that had to be the Defender. 

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"Stories about Lake and his inventions fascinated me," Simon said on Monday. "The secret to identifying this historical relic was to connect the available research to the stories. You could say Defender was hiding in plain sight all this time in a waterway I’ve traveled for years."

Simon Lake

This 1923 photo from the Naval History and Heritage Command, shows Simon Lake, inventor of the 92-foot attack submarine Defender.  (Naval History and Heritage Command via AP)

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Poor tidal conditions prevents Simon's dive team from getting to the wreck during their initial attempt on Friday. Two divers, Steve Abbate and Joe Mazraani, descended roughly 150 feet underwater and located the Defender on Sunday.

The Associated Press contributed to this report.