An extendable buoyant board with pairs of telescoping sections which are secured in an extended relation to one another by internal pressure from an inflatable pneumatic bladder enclosed within the sections. By retaining each of the inboard ends of successively smaller pairs of extension sections within the adjacent next larger section, the multisection board, when extended, provides substantial rigidity and strength. The telescoping arrangement is preferably provided by a central tubular section with an opening at each end, and an internal cross-sectional area which diminishes from the center to each opening. A first pair of opposed telescoping tubular extension sections is slidably and non-removably engaged within the outboard end of the interior of the central section.