The Isle of Clairinch, also known as The Flat Island, in Loch Lomond is owned by The Buchanan Society and is currently leased to Scottish Natural Heritage.

It is a small level wooded island covered in oak trees entwined with ivy.  When seen from the air, the shape of the island resembles a fish.

It is in the Lowlands of Scotland but the largest portion of the Parish of Buchanan, which includes Ben Lomond (3192ft, 973m) is in the Highlands.