bass in the boat

I try to work on my boat myself as much as I can and this winter I want some bass. Not too much, I dont need to be the loudest guy on the lake. But when in the boat I want it to ROCK!. Anyway I am hoping I can put a box next to the battery under the passenger seat. My questions are: Will that sound good? Should it be a ported box? Im not the best at speaker knowledge...install is not a problem. I just need to be pointed in the right direction with the right material. Any help would be appreciated. My other thought is that a "built in" sub in front of the driver seat might sound the best..I dont know. Thanks!