Rathmullan is a really peaceful village about a 20 minute drive from Letterkenny. It's got real character and a lot of history; there's an old Abbey where Red Hugh O'Donnell was educated, a battery dating back to the Napoleonic wars and it was the site of the Flight of the Earls in 1607. Of course it also has a beautiful beach with wooded walks running parallel. There's a local riding stables Golden Sands, who organize treks along the beach and around the area. If you're visiting Letterkenny it's worth a venture.