There’s an excellent report on the Santa Barbara natural oil seepage from the Woods Hole Oceanographic Institution. The study documents the 5,280 to 6,600 gallons (nearly 20 to 25 tons) of oil per day that seeps into the area waters and has been active for hundreds to thousands of years. In earlier days local Native Americans used the oil to waterproof their boats.
From the online report:
The water was calm and flat—dampened by a widespread, iridescent film of oil on the surface. Big oil patties floated about. The air smelled like diesel fuel.
By any definition, it was a classic oil spill. But we were the only boat in the area—no Coast Guard, no oil booms, no throngs of cleanup crews in white Tyvek suits, no helicopters, no media, and no shipwreck.
Why? Because this oil spill was entirely natural. The oil had seeped from reservoirs below the seafloor, leaked through cracks in the crust about 150 feet (45 meters) under water. Lighter than seawater, the escaped oil floated to the ocean surface.
Read more & view photos: While Oil Gently Seeps from the Seafloor