A resemblance to the jet of compressed air and water vapor expelled by whales may explain the geological terms blowhole and the more geyser-like spouting horn. Along sea cliffs where rock is prone to developing fissures, blowholes—narrow openings to the surface—may develop when the force of waves compresses air within clefts or sea caves. Along the coasts of volcanic islands, such as those that comprise Hawai’i, lava tubes sometimes supply the seaward openings, with air and salt water jetting from a portion of collapsed roof. Strong wave action can push spray out through such openings in an explosive plume like a geyser: Spouting Horn at La¯wa‘i, on the south shore of Kaua‘i, can sometimes reach ninety feet. The term blowhole is also used to describe an opening through a snow bridge and into a crevasse where air movement is palpable, or a very small opening through which gas escapes on the surface of a lava flow.

Pamela Frierson