Grassholm Island

Grassholm (Welsh: Gwales or Ynys Gwales) or Grassholm Island is a small uninhabited island situated 13 kilometres (8 mi) off the southwestern Pembrokeshire coast in Wales, lying west of Skomer, in the community of Marloes and St Brides. It is the westernmost point in Wales other than the isolated rocks on which the Smalls Lighthouse stands. Grassholm is known for its huge colony of northern gannets; the island has been owned since 1947 by the Royal Society for the Protection of Birds, and is one of its oldest reserves. It reaches 42 metres (138 ft) tall. Grassholm National Nature Reserve is the third most important site for gannets in the world, after two sites in Scotland: St Kilda and Bass Rock. It serves as a breeding site for 39,000 pairs of the birds, and supports around 10 per cent of the world population. The turbulent sea around Grassholm is a good feeding area for porpoises and bottlenose dolphins. The island has a significant problem with marine plastic, brought to the island by breeding gannets, as nesting material which the birds have mistaken for seaweed floating in the surrounding waters. The problem has been ongoing through twelve years of RSPB conservation to 2017, and surveys have indicated that 80% of nests contain waste plastics. Boats sail to Grassholm from St Davids Lifeboat Station and Martin's Haven on the mainland, but members of the public are not permitted to land. Geologically, the island is largely formed from keratophyre, though the northwest coast and the islet of West Tump are formed from basalt. A couple of NE-SW aligned faults cross the island. Raised beaches are present in places.