An inflatable motor boat with a U-shaped hull in plan view and configured to operate in shallow water. An inflatable bottom is attached to the hull and comprises an inclined longitudinal tunnel having an arc-shaped form in cross section. A portion of the tunnel is wedge-shaped with an angle of inclination from 5° to 45°. The width of the tunnel can be reduced in a rearward direction, and an upper surface of the tunnel can have a sinusoidal shape in a longitudinal section.