Santa Rosa has a lot to offer. It is a gem on old Route 66 and has a lot of history around the "Mother Road". However, Blue Hole is unique, even along the "Mother Road". Blue Hole appears in the midst of the desert like a great blue gem. (Agua Negra Chiquita) Once known as Blue Lake, it is one of seven sister lakes connected underground by a vast system of underwater caves. The Blue Hole is a circular, bell-shaped pool and is one of the most popular dive destinations in the United States. It is actually an artesian spring and was once used as a fish hatchery. It is clear blue with a constant 62 °F and a constant inflow of 3,000 gallons per minute. The surface is only 80 feet in diameter, but it expands to a diameter of 130 feet at the bottom.