The researchers believe the finding may explain why some sea mammals are able to make such long underwater dives while other mammals can only hold their breath for a few minutes. Sperm whales make some of the longest dives achieved by mammals, with some lasting up to 90 minutes, while dolphins and other whales can stay underwater for 20 minutes. The longest time a human has held their breath for under water is 19 minutes – set by a Swiss freediver called Peter Colat.