Immature animals are similarly impossible to count at sea.
Dense Leatherback nesting occurs along the Pacific coast of Mexico in Michoacan, Guerrero and Oaxaca. If these records refer to a single breeding assemblage, this represents the largest known population. Allowing for other nest beaches in the area, and re-nesting of each turtle after about 10 days, the total number nesting per season may be estimated at 30,000. Multiplying by 2.5 to allow for a two or three year nesting cycle, the total breeding female population using this tri-state area is around 75,000. By far the largest extant sea turtle, approaching 1.8m in length.