Between December and March, thousands of elephant seals – sea mammals weighing up to three tons – come ashore at Ano Nuevo State Reserve to indulge in noisy mating rituals: the males demonstrate their strength before copulating vigorously with 50 or so females. Large crowds of humans go goggled-eyed at this unfor­gettable spectacle: to join them, reserve a place on the three-hour ranger-led tour (http://www.parks.ca.gov/?page_id=22657).