Blue Hole, Natural artesian well in Santa Rosa, United States.

Blue Hole is a circular, bell-shaped artesian pool along Route 66 east of Santa Rosa, New Mexico. Its surface is 80 feet (24 m) across and widens to 130 feet (40 m) at the bottom, which lies more than 80 feet (24 m) down. The water holds a constant 62 °F (17 °C), and a stone-lined edge and pale rock border the pool.

Before the spring became a public recreation area, it served as a fish hatchery for the region. Nomadic groups used the water as a reliable source while traveling through New Mexico.

The name comes from the blue colour of the water, not from minerals: the pool is fed by an artesian spring rising from deep underground. Local legend holds that its flooded passages may connect to Carlsbad Caverns, over 200 miles south. Divers from around the world train here, and goldfish, koi, carp and crawdads live in the pool.

The pool sits at 4,616 feet (1,407 m) elevation, so divers must use high-altitude dive tables to plan profiles and decompression stops. A short wall rings the pool to keep surface runoff from clouding the water. Cave passages below are sealed by a metal grate; visitors can swim, snorkel and dive in the open pool.

The cave passages below the pool were sealed with a metal grate in 1976 after a diver went missing; state police divers mapped part of the system during the search. The grate was opened only between 2013 and 2016, when the ADM Exploration Foundation mapped the caverns.