Starter Pack

I usually do experiences for my husband's birthday. He's an engineer so we've done tours of different kinds of plants (steam plant, steel, etc). There's a rent an electric boat place that he likes that's pretty cheap so we've done that a few times. Is there a place in your town he's wanted to go or something he's wanted to do? $500 can get him a great experience! (you could probably also pay a lot less too)