Grassholm or Grassholm Island is a small uninhabited island situated 13 kilometres 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 o…Grassholm or Grassholm Island is a small uninhabited island situated 13 kilometres 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.