Mare Island and the now closed Mare Island Naval Shipyard have seen it all, from canvas to coal to oil to nuclear power, from sailing ships to steamers to nuclear-powered submarines, Mare Island has played an important part in American, Naval, and Vallejo history. According to legend, the island once known as Isla Plana got its current name from General Mariano Guadalupe Vallejo himself. The story goes that one day some of General Vallejo’s animal stock was being moved across San Pablo Bay on a rickety old raft when a wind squall capsized it in the bay. One of the more prized passengers on board, a nameless old white mare saved herself by swimming ashore. She was discovered later living on the island. General Vallejo removed his horse and gave the island a new name, Isla de la Yegua, or Island of the Mare.