Arena Canyon has steep-sided gorges on the seafloor of the continental slope, west of Mendocino County, CA. Arena Canyon is approximately 18 kilometers (11 miles) long, at its widest point is 3 kilometers (2.8 miles) wide, and ranges in depths from -200 meter depth to -1590 meters depth. The head of the canyon is approximately 18 kilometers (11 miles) west of Point Arena, off of the Mendocino County coast. The northern wall of Arena Canyon displays extensive deepwater coral forests that feature a variety of species, including bamboo, bubblegum, black, and mushroom corals; primnoids (Callogorgia sp.); and Plexauridae (Swiftia sp.).