Subic Bay is a bay on the west coast of the island of Luzon in the Philippines, about 100 kilometers northwest of Manila Bay. An extension of the South China Sea, its shores were formerly the site of a major United States Navy facility, U.S. Naval Base Subic Bay, now an industrial and commercial area known as the Subic Bay Freeport Zone under the S…Subic Bay is a bay on the west coast of the island of Luzon in the Philippines, about 100 kilometers northwest of Manila Bay. An extension of the South China Sea, its shores were formerly the site of a major United States Navy facility, U.S. Naval Base Subic Bay, now an industrial and commercial area known as the Subic Bay Freeport Zone under the Subic Bay Metropolitan Authority.