Suddenly and silently, from out of the boiling surf come thousands upon thousands of turtles. Soon a normally deserted beach in Costa Rica disappears under the weight of an Arribada - the Spanish word for this frenzy of mass nesting which is one of the great mysteries of the sea.

This rarely seen spectacle has been filmed by David Hughes, who spent many months investigating the turtles' strange behaviour and the even more dramatic events that follow the laying of ten million eggs on one tiny beach. For, as the eggs hatch, the predators move in - sharks, vultures, iguanas and even crabs lie in wait for the start of one of the most remarkable struggles for survival in the animal world.

BBC Bristol