Looking for something cheap to do in Western Massachusetts this July 4th weekend?

I'm hoping to get some leads on some fun things to do in Western Massachusetts this 4th of July weekend with my boyfriend. I don't have much money to spend but we love zoos and aquariums or maybe a beach somewhere. I'm not looking to go all the way to the Eastern Coast though as I'm planning a day trip, preferably without huge parking fees. Any suggestions?