Looking for a waterproof subwoofer for boat and a stereo to control it? From boats and ATVs to indoor/outdoor marine and spa environments and more, if you’re looking to boost your sound quality, the SWA6+ Combined Waterproof Stereo System with Subwoofer could be the answer. This stereo-subwoofer boasts an 8″ cone to amplify your bass for the perfect vibration.