Skatepark is right beside the Westport Greenway (also known locally as the Railway Line Walk) at the junction of the Louisburgh and Leenane roads.
Open all day
Triangle shaped street style park, one taco style quarter, nice big flat banks and selection of rails and ledges.
Unless you're from out that way it's a real long way to go but it's a fun park so definitely should be on everyone's bucket list. Not much in the way of transitions though!
Hard to find but ask in the tourist office in westport.