St Ninian's Isle is a small tied island connected by the largest active tombolo in the UK to the south-western coast of the Mainland, Shetland, in Scotland. The tombolo, known locally as an ayre from the Old Norse for "gravel bank", is 500 metres long. During the summer the tombolo is above sea level and accessible to walkers. During winter, stronger wave action removes sand from the beach so that it is usually covered at high tide, and occasionally throughout the tidal cycle, until the sand is returned the following spring. Depending on the definition used, St. Ninian's is thus either an island, or a peninsula; it has an area of about 72 hectares. The nearest settlement is Bigton on South Mainland. The important early medieval St Ninian's Isle Treasure of metalwork, mostly in silver, was discovered under the church floor in 1958. Many seabirds, including puffins, visit the island, with several species nesting there.
As its name suggests, the island has ecclesiastical connections, which may like others in the Northern Isles, Hebrides and Faroes have connections to the Culdees or papar. However, the island's history is far older than Christianity, and Neolithic graves have been found within the walls of the chapel (formerly beneath the floor).
Saint Ninian (traditionally 4th-5th century) is a Christian saint first mentioned in the 8th century as being an early missionary among the Pictish peoples of what is now Scotland. For this reason he is known as the Apostle to the Southern Picts, and there are numerous dedications to him in those parts of Scotland with a Pictish heritage, throughout the Scottish Lowlands, and in parts of Northern England with a Northumbrian heritage. In Scotland, Ninian is also known as Ringan, and as Trynnian in Northern England.
Ninian's major shrine was at Whithorn in Galloway, where he is associated with the Candida Casa (Latin for 'White House'). Nothing is known about his teachings, and there is no unchallenged authority for information about his life.
A link between the Ninian of tradition and a person who actually appears in the historical record is not yet confirmed, though Finnian of Moville has gained traction as a leading candidate. This article discusses the particulars and origins of what has come to be known as the "traditional" stories of Saint Ninian.