Dive angles for a green turtle (Chelonia mydas)

The depth and swim speed of a green turtle (Chelonia mydas) were measured d uring the internesting period in Cyprus. For dives to the seabed (U-dives) we used these data to determine dive angles. Typically the turtle initially descended at a steep angle (similar to 60 degrees) but as the dive continu ed this angle lessened until the turtle approached the seabed at an average angle of similar to 15 degrees. This systematic change in descent angle is consistent with the prediction that the energetic implications of dive ang le are most important at the start of the dive when the turtle is fighting to overcome its positive buoyancy. On leaving the seabed, the turtle often seemed to rise passively.