Carlsbad Caverns National Park in the Guadalupe Mountains of southeastern New Mexico is one of the most important cave parks in the United States, centered on Carlsbad Cavern and the immense Big Room, the largest chamber in North America. The caverns formed over millions of years as sulfuric acid dissolved ancient limestone from a Permian reef, and later water deposits created striking formations such as stalactites and stalagmites. Modern exploration became closely associated with Jim White, who entered the cave in 1898 and named many of its famous features. Protected first as a national monument in 1923 and a national park in 1930, it also includes extensive wilderness and historic districts.