Leatherback sea turtles reproduce sexually and generally mate between the months of April and November.  They often travel thousands and thousands of miles to find a mate. Once a potential mate it located, the male will nip at her neck and flippers in a means to court her. If the female accepts his advances, he climbs on to her back and wraps his tail under her tail and extends his penis from his cloaca to her cloaca. Once mating is completed the female will venture away and mate with other males, storing sperm for several months until she is ready to begin fertilizing eggs. Mating can actually be very dangerous for sea turtles as the female must support the weight of herself plus the male while still being able to surface for air. Other male turtles may try to approach the female and essentially fight off the other male to make his own advances. 

Nesting season lasts from March to July in the northern hemisphere and November through February in the southern hemisphere.  A female leatherback turtle will swim ashore at night making herself extremely vulnerable.  Females moving very slow and do not have many means of defense. The leave behind huge tracks until the locate a spot near grassy banks where they dig massive nests. They will return to this same nest multiple times at approximately 8 to 12 day intervals to lay clutches of eggs. Once she is finished, the nest will have around 100 eggs.  She will then cover the nest with sand and return to the ocean. The eggs will hatch in about 2 months. She will return to the area in another 2 to 4 years to nest again. 

Approximately 2 months from the female depositing the eggs in the nest, the little hatchlings begin making their appearance. They are only about 2 to 3 inches at this stage. They dig out of the sand and using their sense of smell, sniff out the shrimp in the water and make their way towards the ocean. The tiny hatchlings are often swooped up by gulls before they make it to the water. An interesting fact is the temperature of the nest determines the sex of the turtles. The warmer the nest is, more females will be produced whereas the cooler nest produce more males. Leatherback sea turtles grow faster than other sea turtles but it is unknown exactly how long maturation takes. Estimates are approximately  9 to 20 years of age.