Finally , he discovers the largest turtle , the giant leatherback , also laying eggs .
On a Costa Rican beach , Attenborough observes female ridley turtles arriving at the rate of some 5,000 an hour to deposit their eggs .
Attenborough discovers the largest turtle , the giant leatherback , also laying eggs .
On a Costa Rican beach , Attenborough observes female ridley turtles arriving at the rate of some 5,000 an hour to deposit their eggs .