Hot Spring Basin is located 15 miles (24 km) north-northeast of Fishing Bridge and has one of Yellowstone's largest collections of hot springs and fumaroles. The geothermal features there release large amounts of sulfur. This makes water from the springs so acidic that it has dissolved holes in the pants of people who sit on wet ground and causes mounds of sulfur three feet (1 m) high to develop around fumaroles. The very hot acidic water and steam have also created voids in the ground that are only covered by a thin crust.