This is a beautiful place to visit at the top of the Yarrow river valley above Selkirk. The drive is around 45 minutes from Melrose through stunning Scottish landscapes of high hills and deep valleys. For anyone with a road bike its also a fantastic cycling route along quiet roads with incredible scenery. On a sunny summer’s day it’s a great place to take a picnic and have a paddle or a swim. Dogs and children will be in heaven! St Mary’s Loch is the largest natural loch in the Scottish Borders at 5km long and 1km wide. Immediately upstream of St Mary’s Loch and connected via a narrow channel is the slightly smaller Loch of the Lowes. There is a café, sailing club and the Tibbie Shiels Inn pub over looking the loch.
https://en.wikipedia.org/wiki/St_Mary%27s_Loch
http://www.stmlsc.org.uk/