Skomer is a national nature reserve less than a mile off the tip of the Marloes peninsula, run by the Wildlife Trust of South and West Wales. It is one of the great wildlife sights of Britain. Around 40,000 puffins nest in burrows here between mid-April and July, and they are remarkably tame, landing beside the paths with beaks full of sand eels. The island also holds around 350,000 pairs of Manx shearwaters, about half the world's population, along with guillemots, razorbills, kittiwakes and short-eared owls. The Skomer vole lives nowhere else.
Boats run from Martin's Haven, a fifteen-minute crossing, daily except Mondays from April to September, weather permitting. Landings are limited, so book ahead. Puffins are gone by the end of July. Visitors keep to the paths, and there is a small hostel on the island for overnight stays.