The Exploris Aquarium in Portaferry (County Down) is a favorite with families touring the Ards Peninsula and Strangford Lough. It is situated near the old tower house in town and good for a few educational hours.
Apart from the usual aquarium stuff (i.e. fish in tanks), the children will love the touch-tanks where you can get to (careful) grips with some sub-aquatic wildlife. Another favorite is the seal station where orphaned seals are raised and prepared for a life in the wild.
Exploris is open daily, but check actual opening times for the day you want to visit.

