If you are camping, then you will need to get busses into town (unless you are willing to walk 8KM to get there). The 1st Bus leaves both campsites at 9am heading towards town. There is then 1 bus around every 1-2 hours. If you are in town then makes sure you KEEP TRACK OF TIME - The last bus leaves town, to the directions of the campsites at 6PM. after that, you have the choice to either walk, or get a taxi. The cost of the taxi to each of the campsites is 10 Euro from town. The Bus fare from town to the campsites is around €2.50. Walking will take around 1 hour 45 minutes. When going home, if you go by rail, then the train will leave the station at 7:30am, 1:30pm and 6:00pm.
The buses of Bus Eireann serve Sligo from all major towns in Ireland.
Moreover there are hourly local bus services form Sligo to the surrounding area including the seaside resorts of Rosses Point (30 min) and Strandhill (30 min).
We took the train from Dublin Connolly direct to Sligo in a little over 3 hours. Nice train, comfortable and on time. It was a one-way ticket for 27 Euros (2008). The train is much faster than the bus. We bought snaks at Connolly Station next door on Lord Edward Street, less expensive than on the train.
There are no trains from Sligo to Donegal so we took the bus. It was clean and comfortable and the views of area keep you glued to the window.
Sligo's bus station is next to the railway station on N4 and Lord Edward Street. There is a nice coffee shop with sandwiches in the trains station so you can load up on food there to get you to Donegal. The Bus station doesn't have much to offer; no food or toilets.
About 3 trains per day serve Sligo Station (see photo) from Dublin Connolly Station. The journey takes about 3 1/4 hour.