Just off the R251 below Errigal is a small car park. I would recommend having trekking poles for this hike, both for the boggy area and the mountain. From the car park follow the stream to the base of the mountain. The walk up to the base is quite boggy and some people recommend walking up on the right hand side, about 50m from the stream. After submerging a boot in the bog, I had a look around and actually found it easier to walk in the gully of the stream. From the base of the mountain follow the scree slope up the mountain. After about 100m it will give out to a more solid track. The track heads up to the summit and can be narrow in places with a steep drop to your right. The day I went up the mountain, it was covered in mist from about half-ways so I can’t comment on the views but on a clear day they are supposed to be stunning. Just means I’ll have to do it again. The descent can be quite dangerous over the scree slope (use the trekking poles). A tough and enjoyable climb and one I would certainly do again.