The present invention relates to a variable floor (1) for a body of water, the variable floor (1) including a base portion (2) for location on or within a fixed floor (106) of the body of water and means to adjust the slope of the upper surface of the variable floor (1) relative to the fixed floor (106) or base portion (2) in one or both of a first direction transverse to the direction of travel of waves and in a second direction transverse to the first direction. A wavepool (100) incorporating the variable floor (1) and including variable converging side walls, a kit of parts for the variable floor (1) and a method of controlling wave characteristics is also described.