Crannogs are small artificial, or modified natural islands situated close to the shore of a body of water (lochs, lakes, rivers and estuaries) and sometimes linked to the shore by a causeway.  They are found primarily throughout Scotland and Ireland, although one has been found in Langorse Lake in Wales.

They were used as dwellings and, sometimes, defensive structures, and are thought to have been in use for over five millennia from the Neolithic Period to as late as the 17th/early 18th century, although in Scotland there is little convincing evidence for their existence in the Early and Middle Bronze Age.  The earliest radiocarbon evidence indicates their use in Scotland from the Late Bronze Age/Early Iron Age.

Crannogs were usually constructed as brush, timber or stone mounds into which timber piles could be sunk to support the dwelling above.  However, some were entirely built as free-standing wooden structures.  In the Western Isles timber was in short supply from the Neolithic onwards, so that completely stone crannogs supporting dry-stone architecture are common here.  In some cases the island's perimeter has been surrounded by a dry-stone wall or revetment, presumably to facilitate the levelling of the interior, but in other cases the enclosure wall appears to have been designed for defence, e.g. Caisteal Eoghainn a' Chinn Bhig, Loch Sguabain, Mull.  Eilean Amalaig, Loch Frisa, Mull, which is unusual because it is situated on an entirely natural islet in a sea-loch, also appears to have had a defensive role.  The islands were generally surfaced with loose boulders', although at least one timber sub-structure has been identified.  In Lochnameal, Mull, the boulder causeway to the crannog is reported to be founded on trunks of oak.

Today, crannogs typically appear as small, circular islets, often covered in dense vegetation due to their inaccessibility to grazing livestock, or remain hidden as submerged stony mounds.  They vary in size and changes in water level can cause considerable size variation in individual crannogs, but the majority measure between 12 m and 25 m in diameter.  Some exhibit the remains of small, dry-stone, domestic buildings, tentatively ascribed to the late medieval or early post-medieval periods.  This attribution is supported by documentary evidence concerning two of Mull's crannogs, Caisteal Eoghainn a' Chinn Bhig and the crannog in Loch Bà, both of which were occupied into the 16th century.  Although, excavation of crannogs has been limited, a dug-out canoe was found at Lochnameal during drainage operations in the late 1800s.

Below is a list of the seven known crannogs on Mull.  Click on the highlighted links for more detail.

Caisteal Eoghainn a' Chinn Bhig, Loch Sguabain, Glen More

Eilean Amalaig, Loch Spelve

Eilean Ban, Loch Frisa

Crannog, Loch Assapol, Ross of Mull

Crannog, Loch Ba

Crannog, Lochnameal

Crannog (possible), Loch Poit na h-I, Ross of Mull