A shallow seamount – a barely submerged island in the North Pacific Ocean. It is about 100 miles west of Point Loma San Diego, USA, and about 50 miles south-west of San Clemente Island. It is known for clear water, vast kelp forests and abundant sea life.
It is considered the outermost feature in California’s Channel Islands chain. At various times during geologic history, the Bank has been an island – depending on sea level rise and fall. The last time it was a substantial island was around 10,000 years ago during the last ice age. It is quite possible that this island was visited by the first human inhabitants of the Channel Islands – most notably San Clemente Island, whose seafaring residents would have been able to see “Cortes Island” from high elevations on clear days.
The shallower reaches of the Bank comprise about 15–18 miles of sandstone and basalt and they rise from the ocean floor from 1000 fathoms – or just over a mile in depth. The Bank has been described as a series of mountaintops, but really it is more of the shape of a wave-scoured mesa – with a few hard, basaltic high spots along its length. The shallowest peak, the Bishop Rock – rises to between 3 and 6 feet from the surface, depending on the tides. On very low tides, the rock can be visible in the trough of passing waves. Nine Fathom spot is about 4.5 miles northwest of Bishop Rock and also rises to about 54 feet below the surface. Both are noted scuba diving locations featuring clear water, vast kelp forests and abundant sea life.