"There is a healing well on an island in Loch Maree, which was used for curing lunacy as late as the nineteenth century. Coins and nails, as well as pieces of cloth and rag, were hammered into the trunk of a nearby oak tree. Oak trees were believed to be sacred, and may have reflected a pre-Christian belief.
Loch Maree, one of the most beautiful lochs in Scotland, is also the site of a chapel and remains of a burial ground, which are believed to have been founded by St. Maelrubha, although there also appear to have been older pagan traditions associated with the site. Bulls were sacrificed here, as they were at Applecross, and later the custom was associated with St. Maelrubha's day, 21 April."
Another legend connected with the island is a Romeo and Juliet-esque yarn, of a local girl and a Viking Prince. They got married and lived in a tower on the island. They were very happy but the prince's Viking friends needed him back on the longboat. The couple hatched a plan involving black and white flags that would be displayed on his return to indicate whether they were dead or alive. When the prince sailed back he flew his white flag. But his princess had devised some daft method of testing his feelings, involving pretending to be dead. You can guess the rest. They're supposed to be buried on the island.
Told at length in 'Gairloch in North west Ross-shire' by John Dixon (1886).