Can't afford a real boat? Or just don't want the hassle? Check ebay for the Sun Pleasure Inflatable 6 Person Bay Breeze Party Boat-Float-Lounge.
Though they say the inflatable speed boat seats 6, it's pretty clear it can fit more like 8-10 people, and features a large circular seating area in the rear of the boat with an opening in the center for your feet to go in the water. Plus there's additional seating up front for another 2-3 people (just like on a real boat).
check it out: