How do i open a container that has been sealed for 5 years?

It's a waterproof container meant for holding cell phones and camera's for when you get "slimed" (lol, i got it from a Nickelodeon cruise). Anyways, its plastic and the inside is lined with rubber so when you close it water cant get it. Well, i need it for kayaking and its sealed shut, i seriously cant undo it. The clasp comes undone but the actually thin wont open. Any ideas?How do i open a container that has been sealed for 5 years?
The problem is the rubber seal has stuck to the plastic. The only way to open it is to take a knife and cut along the rubber, but it won't be water tight after that.
The plastic has fused, you would have to cut it. My reccomendation is to get new bags but I personally prefer those green plastic containers that look like ammo cans.How do i open a container that has been sealed for 5 years?
A SAW...or knife
Bang it on the counter?
hey i want one,really the first guy seems right