In an aspect, an inflatable object includes an object body enclosing a chamber to receive air, and a valve mounted to the inflatable object body, including a valve body defining a passageway between the chamber and an ambient environment. The valve body has a shoulder. The valve body defines an outside end, which opens to the ambient environment, and an inside end, which opens into the chamber. The valve includes a one-way flap that is movable between an open position to permit fluid communication between the chamber and the ambient environment through the passageway, and a closed position. The one-way flap is biased to the closed position with a closing force selected to be overcomable to move the one-way flap to the open position by an airflow having a speed that is less than about 48 m/s, and which is at a pressure lower than 1 atmosphere.