From humans who can hold their breath for barely two minutes to sea turtles that can stay submerged for up to seven hours, the range of underwater endurance is astonishing. Sea otters manage around five minutes, dolphins about ten, sperm whales close to ninety, and Cuvier’s beaked whales push the limits at nearly 3.7 hours. Together, they highlight just how dramatically marine species have evolved to master deep‑sea diving.