In a previous post, I wrote about the graveyard of ships that lies outside the straits known as the Golden Gate, the only entrance to San Francisco Bay. Here is a photo of it, taken at relatively low tide (I did not consult tide tables. I just happened to be there.) You can see some of the off-shore rocks that become submerged at high tide.
According to the National Park Service, there have been "countless" shipwrecks in these straits since the Gold Rush of 1849 first brought ships to San Francisco Bay. Many natural features make this entrance perilous, including a channel hundreds of feet deep beneath the bridge. But one feature causes more wrecks than any other: fog.
Among the victims of fog was the the Ohioan, which ran aground in 1936 about where this picture was taken. It's cargo was salvaged for months, and it's skeleton lay exposed for two years. Parts of it can still be seen at low tide.
You can read about other infamous wrecks at the Park Service page linked above.