Abstract: The present invention relates to a method for constructing a unit adapted to float in a body of water, the method comprising the steps of: providing a cavity in the unit such that the cavity is open to the environment surrounding the unit, wherein at least a portion of the cavity is adapted to be located below a still water surface when the unit floats in the body of water, and determining a first value of at least a first parameter relating to required hydrostatic properties for the unit. The present invention also relates to a unit adapted to float in a body of water. The unit comprises a cavity such that the cavity is open to the environment surrounding the unit. At least a portion of the cavity is adapted to be located below a still water surface when the unit floats in the body of water. Moreover, the present invention relates to a use of a cavity in a unit adapted to float in a body of water.