ignored the numerous warning signs and attempted to use the hydrothermal pools as hot tubs (like the stream portion of the creek, these pools alternate in temperature but the eruptions in the pools are of super-heated water in already very hot water). Recent geothermal instability has led to its temporary closure for swimming. Officials are unsure of when (if ever) Hot Creek will officially reopen for swimming. Hydrothermal activity has altered many rocks in the caldera, transforming them into travertine and clay. At the Huntley clay mine white chalky clay called kaolinite is mined; the kaolinite is exposed on the resurgent dome and appears as a brilliant white band. Tourism and hiking The largest tourist attraction in the caldera is the Mammoth Mountain Ski Area: the area offers skiing and snowboarding in the winter, and mountain biking in the summer. The Hot Creek tourist attraction was closed to swimming in 2006 due to increased geothermal activity. Hiking and off-road vehicle driving is available throughout the caldera, and in the glacial valleys of the Sherwin Range, immediately to the south of the caldera. Hikers can hike to several lakes in these glacial valleys, including Valentine Lake, Convict Lake, Lake Dorothy, and Laurel Lakes. Crowley Lake, at the south end of the caldera, is noted for its fishing. The nearest hotel accommodations to the caldera are in Mammoth Lakes, California. There are also campgrounds scattered throughout the caldera, and in the mountains near the edge of the caldera. Fatalities In April 2006, three members of the Mammoth Mountain Ski Area ski patrol died while on duty. All three died from suffocation by carbon dioxide when they fell into a fumarole on the slopes of the mountain while attempting to fence it off. See also List of large volume volcanic eruptions in the Basin and Range Province Glass Mountain Map of Long Valley-Mono area Mono–Inyo Craters Mammoth Geothermal Complex - a geothermal power plant in the area References Further reading External links USGS website for the Long Valley Caldera Complex volcanoes Supervolcanoes Pleistocene calderas Valleys of California Volcanoes of Mono County, California VEI-7 volcanoes Calderas of California Volcanic fields of the Great Basin section Volcanic fields of California Inyo National Forest Pleistocene California Pleistocene North America Hot springs of California