Алвин
In 2007, seven more such structures were discovered off the coast of Santa Barbara, California. The largest of these domes lies at a depth of . The structures were larger than a football field and about as tall as a six-story building, all made completely out of asphalt. The unusual features were first noted by Ed Keller on bathymetric surveys conducted in the 1990s, and first viewed by a team led by David Valentine in 2007, utilizing "DSV Alvin". Samples were brought up for testing at the university campus and the Woods Hole Oceanographic Institution.