Blowhole (geology)

In geology, a blowhole, also called a marine geyser, is a vertical shaft that opens to the surface from a sea cave and shoots out sea spray when waves force water through it. It forms as a coastal sea cave grows landward and upward until it breaks through toward the surface, so that incoming waves compress water and air in the cave and release them through the opening at the top. The height of the spray depends on the geometry of the cave and shaft and on tide level and swell. A blowhole system has three parts: a catchment entrance, a compression cavern and an expelling port. Blowholes are likely where rock along the coast has crevices, often along fault lines and on islands, and on the windward side of a coast that takes strong wave energy. La Bufadora in Baja California, Mexico, is a large example, and blowholes are popular tourist sights.