A long archipelago, set on the eastern shores of the Atlantic Ocean, it attracts a wide variety of seabirds, and thanks to the Gulf Stream a climate more mild than might be expected at this latitude.

The islands provide a natural flyway for migrating landbirds to and from their Arctic breeding grounds and a refuge for windblown vagrants from America and northern Europe.

A few pairs of peregrine falcons survive on coastal cliffs and merlin and common buzzard are not uncommon anywhere on hill and moor.

[3] The Shiant Isles have a large population of seabirds, including tens of thousands Atlantic puffins breeding in burrows on the slopes of Garbh Eilean, as well as significant numbers of common guillemots, razorbills, northern fulmars, black-legged kittiwakes, common shags, gulls and great skuas.

Wading birds on the shore include redshanks, sanderlings, turnstones, oyster catchers, dunlin, curlews, whimbrels, ringed plovers and herons.

[6] Unusual behaviour by St Kilda's bonxies was recorded in 2007 during research into recent falls in the Leach's petrel population.

Other freshwater fish present include Arctic char, European eel, 3 and 9 spined sticklebacks, thick-lipped mullet and flounder.

Offshore, it is common to see seals, particularly in Stornoway harbour, and with luck, dolphins, porpoises, sharks and even the occasional whale can be encountered.

[9] The beach at Village Bay in St Kilda is unusual in that its short stretch of summer sand recedes in winter, exposing the large boulders on which it rests.

[10] Amongst the more exotic species found off the Outer Hebrides, is the giant squid (Architeuthis) – specimens are occasionally washed up on the islands.

Humans introduced species such as European rabbits, blue hares, hedgehogs, brown and black rats, feral cats, minks and polecats.

[12][13] American mink are another introduced species (escapees from fur farms) and cause problems for native ground-nesting birds, the local fishing industry and poultry farmers.

Analysis of their stomach contents demonstrated that the Shiant rats did eat seabirds, but it is impossible to tell if they preyed on live birds or simply scavenged dead remains.

The richness of insect life in Lewis is evident from the fact that carnivorous plants, such as the sundew, thrive in parts of the island.

[27] Lewis was once covered by woodland, but the only natural woods remaining are in small pockets on inland cliffs and on islands within lochs, away from fire and sheep.

Plant life in St Kilda is heavily influenced by the salt spray, strong winds and acidic peaty soils.

[32] Situated on the extreme western point of North Uist, the RSPB reserve at Balranald includes sandy beaches, rocky foreshore, marshes and sand dunes.

South Uist is considered the best place in the UK for the aquatic plant slender naiad (Najas flexilis)[34] which is a European Protected Species.

Nationally important populations of breeding waders are also present, including redshank, dunlin, lapwing and ringed plover.

[40] The Flannan Isles provide nesting for a population of seabirds, including Atlantic puffins, northern fulmars, European storm-petrels, Leach's petrels, common shag and black-legged kittiwakes.

[41] On his death on 14 August 1956, the Marquess of Bute's will bequeathed the archipelago to the National Trust for Scotland provided they accepted the offer within six months.

[44] In 2004, St Kilda achieved a joint 'marine' status for its superlative natural features, its habitats for rare and endangered species, and its internationally important population of seabirds.

The islands share this honour with internationally important sites such as Machu Picchu in Peru, Mount Athos in Greece and the Ukhahlamba/Drakensberg Park in South Africa.

[46] The St Kilda World Heritage Site covers a total area of 24,201.4 hectares (93.4 sq mi) including the land and sea.

[49] Visiting yachts may find shelter in Village Bay, but those wishing to land are told to contact the National Trust for Scotland in advance.

[6] St Kilda's marine environment of underwater caves, arches and chasms offers a challenging but superlative diving experience.

[50] Such is the power of the North Atlantic swell that the effects of the waves can be detected 70 metres (230 ft) below sea level.

[52][53] Fortunately, potential contaminants from the vessel including fuel, oils, bait and stores were successfully removed by Dutch salvage company Mammoet before the bird breeding season in early April.