I noticed a new game recently while at the beach, called Spikeball. I've never seen it before so I decided to do a little research.
Basically, Spikeball is a lot like volleyball except instead of hitting the ball over the net, you hit it onto a circular net/trampoline to volley the ball to your opponents. The game is a two-on-two match, and like volleyball you and your teammate have up to three volleys between you to return the ball on the net. The biggest (and coolest) difference is that with volleyball you must stay on your side of the net. With Spikeball once the ball has been served off the net, you can run wherever you want — there are no sides.
Not only does it make for a really fun beach (or Fourth of July barbecue) game, you'll end up running all over the place trying to get the ball, which means you're bound to burn a ton of calories. The game will run you around $50 and it's a guaranteed good time. I just ordered my set — fingers crossed it gets here by this weekend!