As early as the 1750s, the proposed site of the North Sea Maritime Center at the Historic Tupper Boathouse was listed as "the Boat Lot". The area that includes the Conscience Point Historic Site was owned by the Reeves family for generations. This location on North Sea Harbor provided baymen and pleasure boat owners convenient access to Peconic Bay.

In 1928, Ned Tupper purchased the property and built the current structure circa 1932. The family constructed, sold, stored, and repaired wooden boats until the property was sold in 1959. The property became a private marina and the former boatyard building became a series of restaurants and nightclubs until the location was purchased by the Town of Southampton in 2003 and became a public marina and park.