Sea turtle hatchlings emerge from subsurface nests on oceanic beaches, crawl to the ocean, and swim out to sea. Once in the water, hatchlings at first swim almost continuously (a period called the frenzy). In this laboratory study, we compared the duration and diel pattern of frenzy and postfrenzy swimming activity among loggerhead, green turtle, and leatherback hatchlings from beaches in ... [Show full abstract] southeastern Florida. The frenzy of all species lasted one day (24 h). After the frenzy, hatchlings continued to swim during the day. Green and loggerhead hatchlings eventually became inactive at night, but leatherback hatchlings typically swam between 15-45% of the dark period. Because the frenzy is temporally similar in all species, its function may also be the same: escape from shallow waters near shore. Postfrenzy differences in diel activity may reflect contrasts among species in foraging, predator avoidance, and energy conservation strategies.