We had a week away in the caravan staying at the lovely Graig Wen site at Arthog. Here are a few of the great things that you can get up to in that area of Wales, which are great fun with children:
Catch the train to Harlech. There visit the castle and the swimming pool and then catch the train back.
...spend some time just playing on the beach...
...to get back to Morffa Mawddach you can either catch the train back across the bridge, or you can catch the ferry from Barmouth Harbour across to Fairbourne on the other side of the estuary. Then take a ride on the Fairbourne miniature steam railway. Drop one member of the party off at Golf Halt (one of the stops) from where they can walk back along the embankment to pick the car up at Morffa Mawddach and meet you back at Fairborne Station.
Go for a walk at the Forestry Commission (Wales) site at Coed y Brenin, where there are brilliant marked walking trails, including one where you have clues and have to spot the wooden cut out animals hidden in the trees on the side of the trail. There's also a brilliant play area, where materials are available for dam building and shelter making. The cafe is also excellent!
As you can tell, we had a fantastic time.