Abstract: A novel stable inflatable or inflated sail board is provided. The sailboard includes a plurality of discrete, gas-fillable or gas-filled, elongated chambers, each chamber having a top skin and a bottom skin, each chamber, when inflated being sufficiently rigid to maintain its shape without any additional support, and to provide a flat bottom surface for contact with water, the chambers being integrally united to provide an elongated float which is of greater length than width. The sailboard also includes a supporting and stiffening rigid frame comprising a plurality of frame sections which are interconnectable with each other in a longitudinal direction, the frame supporting the floatation member and providing additional stiffness and resistance to fore-and-aft bending and torsion.