Smith leatherback turtles use the male-up and female-down posture when mating. In order to avoid slipping off the female turtle's shell during mating, the male turtle's plastron is slightly concave, just enough to catch the female turtle's protruding back shell; as long as Turn the Smith leatherback over and touch the width of the plastron with your fingers to quickly tell the sexes apart.

In addition, you can see the location of the excretory hole, the male Smith leatherback The location is closer to the tail, while the female Smith leatherback is closer to the plastron.