To the north of Sawel is County Londonderry, and to the south, County Tyrone. The summit is high and is composed of crystalline limestone. Around the peak, there is montane heathland, with plant life including heather, bilberries and cowberries, although this is being damaged by hillwalking and grazing. Sawel is the source of the River Faughan, a long tributary of the River Foyle.