The islands are split into three groups: the main cluster of rocks that lie to the northeast include the two principal islands of Eilean Mòr, which is approximately in extent, and Eilean Taighe ; to the south lie Soray and Sgeir Tomain; while the main western outcrops are Eilean a' Ghobha, Roaireim, and Bròna Cleit. The total land area amounts to approximately and the highest point is above sea level on Eilean Mòr.
The geology consists of a dark breccia of gabbros and dolerites intruding Archaeangneiss. In prehistoric times, the area was covered by ice sheets that spread from Scotland out into the Atlantic Ocean. After the last retreat of the ice circa 20,000 years BP, sea levels were as much as lower than at present and it is likely that the existing islands were part of a much larger land mass, although still separated from the Outer Hebrides by many miles of open water. Steadily rising sea levels thereafter would have reduced the land remaining above sea level to its present extent. There are two possible landing places for yachts visiting Eilean Mòr to the east and west, although this may be hazardous given the regular heavy swells.
History
As the name implies, Eilean Taighe hosts a ruined stone shelter. Eilean Mòr is home to the lighthouse and a ruined chapel dedicated to Saint Flannán, which the lighthouse keepers referred to as the "dog kennel" because of its small size. These ruined bothies were described collectively by the Ancient Monuments Commission as The Bothies of the Clan McPhail, or Bothain Chlann ‘ic Phaill. It is not entirely clear to which St Flannan the chapel pays honours. It is likely that the honoree was either the 7th-century Abbot of Killaloe, County Clare, Ireland, or alternatively, the half brother of the eighth century St Ronan, who gave his name to the nearby island of North Rona. There was also a certain Flann, son of an Abbot of Iona, called Maol-duine, who died in 890 and may also have lent his name to these isolated isles. The archipelago is also known as The Seven Hunters. During the Middle Ages, they also may have been called the Seven Haley Isles. Martin Martin lists a number of unusual customs associated with regular pilgrimages to Eilean Mòr, such as removing one's hat and making a sunwise turn when reaching the plateau.
Wildlife
The 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. There is a gannetry on Roaireim. From the late Middle Ages on, Lewismen regularly raided these nests for eggs, birds, and feathers. There is a population of rabbits, brought to the islands by the lighthouse keepers, and crofters from Bernera graze sheep on the most fertile islands. Minke and pilot whales, as well as Risso's and other species of dolphin are commonly observed in the vicinity. The islands became a Site of Special Scientific Interest in December 1983.
In fiction
's poem Flannan Isle is a poetic interpretation of the events of the disappearances. The Flannan Isles are the main setting in Robert W. Sneddons's short storyOn the Isle of Blue Men which was first published in Ghost Stories magazine in April 1927. The Scottish-American author's "atmospheric, Lovecraftian thriller" was reissued by Charles G. Waugh with an alternate ending based on an older story by Sneddon in the Lighthouse Horrors anthology in 1993. Neil Gunn's epic novel The Silver Darlings published in 1941 describes a visit to the islands. Eilean Mòr in particular also features prominently as the location of a murder central to the plot of Coffin Road, a 2016 novel by Peter May. The Vanishing, a 2019 film starring Gerard Butler and Peter Mullan, is set on the isles and inspired by the infamous disappearance.
