I am able to store quite a bit of useful things under the passenger seat of our '20 Prostar. 4 CGA life jackets (we ski on a public lake), two boat fenders, 4 docking lines, an anchor and anchor rope, a tool kit, an oil funnel and oil filter wrench, extra gloves, an extra tow rope and handle, mask, fins, snorkel and weight belt (for course buoy maintenance), a roll of paper towels, wet suit booties, a boat hook, the plexiglass air dam that slides in the walk through that I've never used (or whatever it's called), the Bimini supports and Bimini cover, fire extinguisher... what else... I'd have to go look, but there is still room to spare. We have the heater, and that takes up some under seat space. Without that there would even be more room. But if the boat has the MTS ballast system it will greatly reduce this under seat storage capacity. There's also a small under-deck storage bin in front of the doghouse where I keep 2 qts of oil. Since, like many, we never use our boat in an open bow configuration, there's ample space in the bow for all kinds of things. But if using it the open bow configuration in protected water, that space would obviously be lost. The port and starboard ski racks are awesome and leave the interior space of the Prostar more generous than the competing models.