[11] This same suite of rocks can also be traced eastwards on the mainland along the northern side of the Marloes peninsula and extends almost as far east as St Ishmael's.

A NW-SE aligned fault stretches between Bull Hole and South Haven, offsetting the strata on either side.

Airborne laser scanning together with ground excavations continued in 2016 and established that human settlement dates back 5,000 years.

[17] Skomer is best known for its large breeding seabird population, including Manx shearwaters, guillemots, razorbills, great cormorants, black-legged kittiwakes, Atlantic puffins, European storm-petrels, common shags, Eurasian oystercatchers and gulls, as well as birds of prey including short-eared owls, common kestrels and peregrine falcons.

The island is also home to grey seals, common toads, slow-worms, a breeding population of glow-worms and a variety of wildflowers.

They arrive in mid-April to nest in burrows, many of which were originally dug by the island's large rabbit population.

By 2004, there were numerous puffin burrows on the island and adults flying back with food run across the walkways oblivious to the tourists.

[20] Shearwaters are not easy to see as they come and go at night, but a closed-circuit television camera in one of the burrows allows subterranean nesting activity to be seen on the screen in Lockley Lodge on the mainland at Martin's Haven.

The young Manx shearwaters remain at sea for five years before returning to breed on their natal island.

As they are ungainly and vulnerable on the land, they leave their burrows only at night to avoid predation by gulls also breeding on the island.

The lack of land-based predators on the island means that the bracken habitat is an ideal place for the vole, with the population reaching around 20,000 during the summer months.

Then the resident short-eared owls may be seen patrolling the areas close to the farmhouse in the centre of the island for voles to feed their young.

The Dale Princess sails to Skomer from Martin's Haven on the mainland, a sheltered 15-minute trip every day (weather dependent) except Monday (Whitsun Bank Holiday Monday excepted) from April to September between 10am and noon (actual times may vary).

Overnight guests are brought over on a separate boat trip on the morning of their stay and the hostel is open April to September.