St Margaret's Island is a small island

Island

An island or isle is any piece of sub-continental land that is surrounded by water. Very small islands such as emergent land features on atolls can be called islets, cays or keys. An island in a river or lake may be called an eyot , or holm...

 adjoining Caldey Island

Caldey Island

Caldey Island lies south of Tenby in Pembrokeshire, Wales.The island is home to a small village, but is best known for its monastery. Caldey Island is separated from the mainland by the Caldey Sound which is 1 km to 2 km wide between Caldey Island and the coast of Pembrokeshire...

 in Carmarthen Bay

Carmarthen Bay

Carmarthen Bay is an inlet of the south Wales coast. The coastline includes famous beaches, including the Pendine Sands and Cefn Sidan sands, and is partially covered by the Pembrokeshire Coast National Park....

, Wales

Wales

Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...

. Its name derives from a chapel

Chapel

A chapel is a building used by Christians as a place of fellowship and worship. It may be part of a larger structure or complex, such as a church, college, hospital, palace, prison or funeral home, located on board a military or commercial ship, or it may be an entirely free-standing building,...

 that once stood on the site; however, in Victorian times this was converted into housing

House

A house is a building or structure that has the ability to be occupied for dwelling by human beings or other creatures. The term house includes many kinds of different dwellings ranging from rudimentary huts of nomadic tribes to free standing individual structures...

 for local quarry

Quarry

A quarry is a type of open-pit mine from which rock or minerals are extracted. Quarries are generally used for extracting building materials, such as dimension stone, construction aggregate, riprap, sand, and gravel. They are often collocated with concrete and asphalt plants due to the requirement...

 workers, who mined limestone

Limestone

Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....

 on the island until 1851.

St Margaret's Island is a sensitive conservation site because of the birds that nest in its cliffs: cormorant

Cormorant

The bird family Phalacrocoracidae is represented by some 40 species of cormorants and shags. Several different classifications of the family have been proposed recently, and the number of genera is disputed.- Names :...

s (the largest population of this species in Wales, constituting 3% of the total British population), guillemot

Guillemot

Guillemots is the common name for several species of seabird in the auk family . In British use, the term comprises two genera: Uria and Cepphus. In North America the Uria species are called "murres" and only the Cepphus species are called "guillemots"...

s, razorbill

Razorbill

The Razorbill is colonial seabird that will only come to land in order to breed. It is the largest living member of the Auk family. This agile bird will choose only one partner for life and females will lay one egg per year. Razorbills will nest along coastal cliffs in enclosed or slightly exposed...

s, shags

Common Shag

The European Shag or Common Shag is a species of cormorant. It breeds around the rocky coasts of western and southern...

, kittiwake

Black-legged Kittiwake

The Black-legged Kittiwake is a seabird species in the gull family Laridae.This species was first described by Linnaeus in his Systema naturae in 1758 as Larus tridactylus....

s, great black-backed gull

Great Black-backed Gull

The Great Black-backed Gull is the largest gull in the world, which breeds on the European and North American coasts and islands of the North Atlantic...

s, lesser black-backed gulls

Lesser Black-backed Gull

The Lesser Black-backed Gull is a large gull that breeds on the Atlantic coasts of Europe. It is migratory, wintering from the British Isles south to West Africa...

, herring gulls, puffin

Puffin

Puffins are any of three small species of auk in the bird genus Fratercula with a brightly coloured beak during the breeding season. These are pelagic seabirds that feed primarily by diving in the water. They breed in large colonies on coastal cliffs or offshore islands, nesting in crevices among...

s and, more recently, gannet

Gannet

Gannets are seabirds comprising the genus Morus, in the family Sulidae, closely related to the boobies.The gannets are large black and white birds with yellow heads. They have long pointed wings and long bills. Northern gannets are the largest seabirds in the North Atlantic, with a wingspan of up...

s. The island is vegetated with sea beet

Beet

The beet is a plant in the Chenopodiaceae family which is now included in Amaranthaceae family. It is best known in its numerous cultivated varieties, the most well known of which is the purple root vegetable known as the beetroot or garden beet...

, sea mayweed

Mayweed

Matricaria is a genus of flowering plants in the sunflower family . Some of the species have the common name of "mayweed," but this name also refers to plants not in this genus....

 and rank grass

Grass

Grasses, or more technically graminoids, are monocotyledonous, usually herbaceous plants with narrow leaves growing from the base. They include the "true grasses", of the Poaceae family, as well as the sedges and the rushes . The true grasses include cereals, bamboo and the grasses of lawns ...

.

There is no public access to St Margaret's Island. However, the waters around it are popular with divers

Diving

Diving is the sport of jumping or falling into water from a platform or springboard, sometimes while performing acrobatics. Diving is an internationally-recognized sport that is part of the Olympic Games. In addition, unstructured and non-competitive diving is a recreational pastime.Diving is one...

.