The lake (originally referred to on maps as Lake Wyandanch and commonly referred to as the "Great Lake") was a freshwater lake until 1927 when Carl Fisher blasted a hole on the northern shoreline to connect it to Block Island Sound and the open waters of the Atlantic Ocean. Before the entrance to Montauk Harbor was created, the Great Lake was the largest body of freshwater on Long Island, more than double the size of Lake Ronkonkoma.
Fisher's efforts were intended to use the lake as the port of his planned development to turn Montauk into the "Miami Beach of the North." On Star Island, a small island in the lake, he built the Montauk Yacht Club and Star Island Casino. His other projects included Montauk Manor, Montauk Playhouse, Montauk Downs golf course, and the six-story Montauk tower. Fisher renamed the lake Lake Montauk.
After Fisher opened and dredged the lake, the lake replaced Fort Pond Bay as Montauk's main port (Fort Pond Bay is notoriously shallow and rocky with one of its more famous groundings being the HMS Culloden during the American Revolution).
After World War II, the lake boomed with commercial and sports fishing, and became New York's largest fishing port.
Montauk has several shark tournaments with boat operator Frank Mundus often being reported in stories as the source for the character Quint in Jaws (film) (Jaws author Peter Benchley's denials of this has not altered the myth). Mundus reputation is encouraged by catching a 4,500 pound (2,040 kg) great white shark by harpoon and a 3,427 pound (1,554 kg) great white by rod and reel.
A proposal in the 1970s called for damming Fisher's access to the Sound and instead building a canal through the former Montaukett Indian Field and Big Reed Pond for a new outlet onto the Sound. The plan called for construction of more than 1,000 houses along the new waterway. Intense local opposition organized by Hilda Lindley stopped the plan. Suffolk County took over the property and it is now Theodore Roosevelt County Park (formerly Montauk County Park).
- Rattiner, Dan (December 4, 2009). "Taking the Beach Private in Lake Montauk". Dan's Papers. Retrieved 2010-01-31.
- Penny, Larry (February 4, 2010). "Lake Needs a Flush". The East Hampton Star. Retrieved 2010-02-06.
- Gall, Ken (Fall–Winter 1994), Montauk - New York's Largest Fishing Port, New York's Seafood Council, retrieved 2010-01-31
- "Fishing - Montak's Lifeblood". Montauk Life. Retrieved 2010-01-31.
- Porco, Jane Powers (2005). "1". Holding Back the Tide: The Thirty-Five Year Struggle to Save Montauk (PDF). Sag Harbor: Harbor Electronic Publishing. ISBN 1-932916-05-9. Retrieved 2010-01-31.
- "Viking Fleet Interstate Fast Ferry". VikingFleet.com. Retrieved 2012-08-20.