Ideas on what to do with so today

We live by the beach, the temp is slightly chilly. (Remember it gets colder on the beach) and it's very cloudy and looks like it is going to rain. We live in a big city and everything you can imagine doing we have it here. We don't want to spend too much money. I would love something that is 20 or under. :) I just want to spend some quality time with him :) info on him: he loves sports, hates large groups of people, hates the mall. Haha help! :) suggestions?