The revolutionary second chamber acts like a surrounded and double side-wall I-beam structure, which increases the hull's stiffness significantly. Covers nearly half of the total board, and places just behind the bungee cords then all the way down to the end of foot pad. The added chamber is strategically placed in the standing area, which overcomes the "soft" and "unstable" disadvantages of an air SUP - therefore providing a very stable riding experience even in the choppy water or stronger wind.