Secca della Colombara is a boat-accessed shoal off Ustica with a shallow crown, steep basalt walls, a broad plateau, and a cargo-ship wreck on the outer slopes. The site can be dived as a flexible loop or out-and-back profile depending on the chosen line, with blue-water pelagic runs around the perimeter and a quieter feel close to the crown. Plan for clear water, current on the exposed edges, and a calm sea state if you want the easiest version of the dive.