Mount Errigal is the most distinguished mountain in Donegal, located between Gweedoor and Letterkenny, this mountain has a very pointy top (not pictured, because clouds). It has a well known hiking path for tourists and locals to peek the mountain, considering the size of this mountain I would estimate that you do need to have supplies and be a good walker to do this trek, which can be done within a day. This picture is taken from outside the An Chuirt hotel on the other side of the road where you can pull in and park.