Treasure Island is a man-made island in the San Francisco Bay between San Francisco and Oakland. It is right next to Yerba Buena Island, a naturally-formed island.

It was created in 1939 for the World's Fair by dredging up dirt from the San Francisco Bay.

In WWII it became part of the Treasure Island Naval Base. In 1996 it and the Presidio Army Base were decommissioned, and opened to public control, under stipulations.