Many park visitors descend to Crater Lake along the Cleetwood trail, from whence they may travel to Wizard Island and around the lake on tour boats operated by Crater Lake Lodge. Four tour boats and a NPS research boat are on the lake. Structures used for boat maintenance and to house the boats during the winter are located on Wizard Island. These facilities, and the people who use them, would be at risk if there were a major disturbance of the lake surface. An event that could result in such a disturbance would be failure of part of the caldera wall causing a rapidly-moving landslide or rock fall into the lake or beneath its surface and which could result in one or more large waves that would travel rapidly across Crater Lake and impact its shore. Landslides or rock falls could be triggered within the caldera by earthquake shaking.