Abstract: This invention relates to spray apparatus for spraying water onto the ground or floor of an indoor riding arena having outwardly inclined boards provided around its periphery, said boards having mounted on their rear side a spray or sprinkler unit which is pivotally mounted by a mounting, the unit being located within a housing which can move with the unit from an inoperative position in which the unit and housing are retracted towards an operative position in which the unit and housing protrude from the front surface of a said board and the spray unit protrudes from the housing, the unit and housing being biassed towards the inoperative position by a weight and moved towards the operative position by a piston and cylinder device which is supplied with water under pressure from the supply conduit for the unit.