I am looking at public transport options to get from Dublin to Glendalough in August and I think I can see a train trip through Naas or coastal via Bray or bus (181). The bus looks potentially shorter and easier but is it worth looking at planning around either of the train options as a more scenic option?
The St Kevin's Bus 181 from Dublin seems to be quite a limited service.
The 183 from Sallins & Naas station to both Arklow and Wicklow provides more journey opportunities. I am a great believer in doing circular trips if they make sense, and in this case it seems to.
The train journey to Sallins and Naas is just an ordinary commuter trip, but the Rosslare bound trip to Wicklow and Arklow through Bray is a scenic coastal train route and well worth doing.
Outbound the rail to bus connections through Wicklow and Arklow work well, not so well inbound.
So inbound I would either take the 181 or the via Sallins and Nass route- the connections via Sallins work well on a weekday.
Not sure what your plans are after Glendalough, but there is a Paddywagon Tour bus that goes to Glendalough visitors center, and then on to Kilkenny after about an hour or so. You could always get off at Glendalough and stay off. Just tell your guide. There is even room for luggage under the bus. It seems mostly used by college aged adults, but it’s a nice vibe, not rowdy, plus a bit of narration on the way from the guide. No stops or changes.