A float tube or watercraft comprised of a generally U-shaped inflatable flotation chamber having two generally parallel and laterally disposed leg portions and a rearward portion. The leg portions are preferably formed integrally with the rearward portion. The invention further includes a seating device bridging the two leg portions of the flotation chamber. A stabilizing frame and system for connecting the stabilizing frame to the U-shaped flotation chamber provides support to the opposing legs of the flotation chamber and prevents them from pinching in on the occupant, and also preferably tensions a seat provided between the legs of the floatation chamber. For additional support and/or this preferred tensioning, a rigid and/or adjustable rod, or tube, extends between the opposing legs of the frame. The system for connecting the stabilizing frame comprises preferably a plurality of channel segments, which are fixedly secured to the leg and rearward portions of the flotation chamber. Alternatively, a continuous channel may be used.