Subic Bay on the island of Luzon.. Subic Bay opens seaward to the southwest with Grande Island, located in the mouth of the bay, dividing the entrance into two channels. The main channel, lying to the west of Grande Island is wide, deep, and clear of obstructions.  When Subic Bay was a US Navy installation, all facilities were available for assignment to US Navy vessels.  The base closed in 1992 with the cessation of the treaty between the Philippine Republic and the United States of America.