I have a fairly decent 13yr old on the premises - however, as he goes sailing and adventuring with his father, I'm at a loss to do something in the holidays which will keep us both entertained. He's not wildly keen on museum-y things and a suggested trip to Madrid has been shot down as it is not near the sea. (We already live near the sea but seemingly variety not a spice he's doing this year). Any suggestions ? Thank you