A wave forming apparatus has a channel for containing a flow of water with an inlet end connected to a water supply, a base, and spaced side walls, a first bed form or weir at the inlet end of the channel, and a second bed form in the channel downstream of the first bed form. Each bed form has an upper portion and a downwardly inclined downstream face extending from the upper portion to a trailing end. The trailing end of at least the first bed form is an extended, horizontal tail portion which extends up to an upwardly inclined leading face of the second bed form.