Eilean Choraidh, also known as Horse Island is an island in Loch Eriboll

Loch Eriboll

Loch Eriboll is a long sea loch on the north coast of Scotland, which has been used for centuries as a deep water anchorage as it is safe from the often stormy seas of Cape Wrath and the Pentland Firth...

 in Sutherland

Sutherland

Sutherland is a registration county, lieutenancy area and historic administrative county of Scotland. It is now within the Highland local government area. In Gaelic the area is referred to according to its traditional areas: Dùthaich 'IcAoidh , Asainte , and Cataibh...

 on the north coast of Scotland. It is about 20 hectares (49.4 acre) in extent and the highest point is 26 metres (85.3 ft) above sea level.

During the 19th century the Reay

Reay

Reay is a village which has grown around Sandside Bay on the north coast of the Highland council area of Scotland. It is within the historic Parish of Reay and the historic county of Caithness....

 estate quarried lime from Eilean Choraidh, treated it in kilns on the nearby peninsula of Ard Neakie, and exported it by ship.

The census of 1931 records a single male inhabitant, and there has been no indication of any permanent residents since then. This may be partly because Eilean Choraidh was used as a representation of the German battleship

Battleship

A battleship is a large armored warship with a main battery consisting of heavy caliber guns. Battleships were larger, better armed and armored than cruisers and destroyers. As the largest armed ships in a fleet, battleships were used to attain command of the sea and represented the apex of a...

 Tirpitz

German battleship Tirpitz

Tirpitz was the second of two s built for the German Kriegsmarine during World War II. Named after Grand Admiral Alfred von Tirpitz, the architect of the Imperial Navy, the ship was laid down at the Kriegsmarinewerft in Wilhelmshaven in November 1936 and launched two and a half years later in April...

for target practice by Mosquito

De Havilland Mosquito

The de Havilland DH.98 Mosquito was a British multi-role combat aircraft that served during the Second World War and the postwar era. It was known affectionately as the "Mossie" to its crews and was also nicknamed "The Wooden Wonder"...

 bombers of the Royal Air Force

Royal Air Force

The Royal Air Force is the aerial warfare service branch of the British Armed Forces. Formed on 1 April 1918, it is the oldest independent air force in the world...

 during World War II

World War II

World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

. The Ordnance Survey

Ordnance Survey

Ordnance Survey , an executive agency and non-ministerial government department of the Government of the United Kingdom, is the national mapping agency for Great Britain, producing maps of Great Britain , and one of the world's largest producers of maps.The name reflects its creation together with...

 indicate the presence of two ruined buildings, one in the centre of the island north of a long wall that runs east to west and another at the north end. Today, the island is used for grazing sheep.

A variety of wild mammals are present including Otters

European Otter

The European Otter , also known as the Eurasian otter, Eurasian river otter, common otter and Old World otter, is a European and Asian member of the Lutrinae or otter subfamily, and is typical of freshwater otters....

, Grey Seal

Grey Seal

The grey seal is found on both shores of the North Atlantic Ocean. It is a large seal of the family Phocidae or "true seals". It is the only species classified in the genus Halichoerus...

s and cetaceans. Beds of maerl

Maerl

Maerl is a collective name for Coralline red algae with a certain growth habit. It accumulates as unattached particles and forms extensive beds in suitable sublittoral sites.-Description:...

, a corraline

Coral

Corals are marine animals in class Anthozoa of phylum Cnidaria typically living in compact colonies of many identical individual "polyps". The group includes the important reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton.A coral "head" is a colony of...

 algae

Algae

Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...

 that has been identified as a priority habitat in the UK
Biodiversity Action Plan, has been recorded in the channels on either side of Eilean Choraidh. The sea pen,
Virgularia mirabilis is also present in the inner loch.
Further north, at the entrance to the loch, is Eilean Hoan

Eilean Hoan

Eilean Hoan is an island in Loch Eriboll in Sutherland on the north coast of Scotland. It is about in extent and the highest point is above sea level. Its name is of Gaelic and Old Norse derivation and means "haven island"....

.