In reply to olddirtydoggy:
Coasteering, kayaking, whitewater rafting, all of which have instructors in north wales who can take you out and provide equipment. The nice thing about whitewater is that it is at is finest when it has been tipping it down the night before, so quite complementary with climbing.
Going round a castle - mist swirling around the battlements can add to the romantic charm. Plus there is often an indoor museum bit with suits of armour, handy if you have kids and they are getting cold and bored outside. Similarly, steam train rides, butterfly gardens and so on are good for kids in Wales.
Pick a lake on the map and go for a swim in it. Or why not try bog snorkelling? You’ll be wet and muddy anyway from the walk in.