The Aquadome, Tralee
The aquadrome is heavily promoted as a 'must see' tourist destination. In truth the giant wigwam is no more than a fairly pleasant swimming pool with a couple of slides attached. We visting in March, and I can't even claim that it was warm inside. The water temperature is fine, but you can start to shiver out of the water for a while.
The two main slides feature the 'raging rapids' which is a wide outside flume with lots of water. It's fairly short, but fun.
The longer traditional flume features a timing feature. The best time I recorded on my visit with the family was 10.96 seconds. I believe (according to the lifeguard) that the Jusain Bolt's of the waterslide world can command a time comfortably under the magic 10 second barrier.
At getting on for 20 euro for a family visit you can't call it cheap, but at least it is in the dry (well its very wet,but at least you don't get rained on) and there is no time limit on a visit. Will keep kids under 10 happy, but older ones will find it a little tame.