Denny Island

Denny Island (Welsh: Ynys Denny; grid reference ST459810) is a small uninhabited rocky island of 0.24 hectares (0.6 acres), with scrub vegetation, in the Severn Estuary. Its rocky southern foreshore marks the boundary between England and Wales. Above high water mark, the island is reckoned administratively to Monmouthshire, South Wales. The island also marks the north-western limit of the City of Bristol's water boundary in the Severn estuary. It is located approximately three miles north of Portishead, midway between Redwick in Wales and Avonmouth in England. It is surrounded by sandbanks known as the Welsh Grounds. Its foreshore area changes dramatically according to the state of the tide, because tides in the estuary and Bristol Channel are amongst the highest in the world, reaching 13.7 m (45 ft) at the spring equinox. It is known as a nesting-place for gulls, cormorants and other seabirds, which are regularly seen and ringed there.