Leatherback sea turtles (Dermochelys coriacea) are the largest species of sea turtle, often reaching over 900 kg. The goal of our study, conducted along the beaches of southern Florida is to understand the size of the leatherback population, individual size, migratory patterns, family lineages, and other important aspects of leatherback biology. Studies like ours are critical to help protect this endangered species from the threat of extinction.