USS Dapdap (YFB-684) was a United States Navy working launch in service from 1908 to 1942.

Dapdap (YFB-684), a working launch, was attached to the United States Asiatic Fleet at Naval Station, Cavite, Philippine Islands,[1] or the 16th Naval District from 1908 to 1942.

Dapdap was lost, 2 January 1942, to Japanese forces during the conquest of Luzon Island.

She earned one battle star.

She was stricken from the Navy List on 24 July 1942.