Yellowstone has over 300 geysers, two thirds of all the geysers in the world. It is a volcanic area, with superheated magma deep in the earth heating water that seeps into the earth. This forms an underground plumbing system, regularly forcing great gouts of steam through crevices in the rock that erupt as geysers. Castle Geyser has built up a large cone around its crevices, and when it erupts, steam and water gush into view with great force. Using a focal length of almost 400mm, and a relatively slow shutter speed of 1/30th of a second that turns water and steam into a cloudlike curtain, I express the essence of the geyser’s force as an eruption.