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.

This photo, provided by Shoreline Diving Services, shows the team preparing to dive the wreck of the 92-foot attack submarine Defender, Friday, April 14, 2023, that was scuttled by the Army Corp of Engineers in 1946. (Jennifer Sellitti/Shoreline Diving Services via AP)

This photo, provided by Shoreline Diving Services, shows diver Steve Abbate inspecting a propeller, Sunday, April 16, 2023, of the 92-foot attack submarine Defender that was scuttled by the Army Corp of Engineers in 1946. (Jennifer Sellitti/Shoreline Diving Services via AP)

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.

The Defender, a 9 (Library of Congress Prints and Photographs Division)

This 1907 photo, from Chapman University, Frank Mt. Pleasant Library of Special Collections and Archives, shows the Defender submarine. The wreckage of the Defender submarine, built in 1907 before being rejected by the Navy, has been discovered off the coast of Connecticut in Long Island Sound, Sunday, April 16, 2023, by a group of commercial divers. ( (Chapman University, Frank Mt. Pleasant Library of Special Collections and Archives via AP)

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."

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.

Connecticut dive team locates 116-year-old experimental submarine at the bottom of Long Island Sound

The 92-foot-long Defender was originally built in 1907