Although it does sound like a strange thing to do it can prove to be very relaxing. There are many celebrities such as James Caan who love to drive their boats around as they find it very relaxing.
Although it is very difficult for any normal person to actually own a boat it is not hard to go out and rent one so it is worth giving it a try. If you are thinking about renting a boat out for a day there are actually loads of things you can be doing during the day.
Drive Around
You could do the very obvious one and just take it for a bit of a drive around the sea and enjoy the world for what it is. Of course you could go out and buy a nice captain’s hat for the day.
Swimming/Scuba
Just find a nice location and jump in to feel the warmth of the sea. Do not go near any places that are dangerous as you could end up hurt. It could be an idea to ask around to fins out the best places to go. If of course you are a professional you could always do a bit of scuba diving and watch the creatures of the sea go about their daily routines.
Fishing
Although this can be a good idea be careful where you go off to fish as many places will have you in trouble for fishing in. One of the best things to do is actually ask around to see where you can do the fishing.
One thing I will say is make sure the boat has one of the decent marine batteries in it as you will then get the most out of the boat.
If you are in need of batteries then look into UPS batteries or perhaps some battery accessories