The water in the Great Blue Hole is very calm. There is little to no current throughout the Hole, and the water is completely stagnant at the bottom. The water is warm, with a temperature of approximately 76 degrees F at a depth of 130 feet. There is hardly any temperature change throughout the year. There is a thermocline at about 150 feet and a hydrogen sulfide layer at about 310 feet. The water is fairly clear, and the turbidity decreases at greater depths. The salinity is approximately 36 parts per thousand.