In August 2016 scientist looked at 28 Greenland sharks that were accidentally cot in nets as by-catch by fishermen in the North Atlantic. Through tissue dating they determined that some of the sharks were over 292 years old when they were caught. Their estimates ranged as high as 400 years for those caught, leading to a determination that they would live to 500 years if not accidentally caught.
While the estimates are wide, at over 300 years, and possibly 500 years lifespan, the Greenland shark is the longest living vertebrate. Scientist cannot be certain but believe the low temperatures of the North Atlantic slow the rate of aging for the shark. Whatever the reason, it is remarkable.