Killybegs. In County Donegal is a port rich in culture and history, surrounded by wonderful historic castles and stunning national parks. It is the largest fishing port in the country and on the island of Ireland. It is located on the south coast of the county, north of Donegal Bay, near Donegal Town. Its Irish name Na Cealla Beaga means ‘little cells’, a reference to early monastic settlements. The town is situated at the head of a scenic harbor and the base of a vast mountainous tract extending northward.