Abyss Pool is a hot spring in the West Thumb Geyser Basin of the Yellowstone National Park in Wyoming, United States. The colour of the water is turquoise blue and it is so clear that you can almost see through the water but you can't see the bottom. Hence the name Abyss pool. It is 53 feet deep and is the largest hot spring pool in Yellowstone Lake at West Thumb. Although it is a dormant now it has been an active geyser in the past. Last time it irrupted was in 1992 with plums of water reaching 30 -80 feet in the air.