A balance board has a top side and an under side. The under side is arranged to be mounted on top of a ball with a user balancing on the top side. The board is shaped to define a generally longitudinal direction and a direction generally transverse to the longitudinal direction. The board is formed from a first top portion defining the topside and having a substantially flat region on its under side and a second lower portion joined to the first top portion and defining a wall at least substantially bounding a portion of the flat region. The distance across the bounded portion in the longitudinal direction of the board is greater than in the transverse direction. With the bounded portion balanced on a ball with a diameter less than the distance across the bounded portion in the transverse direction, the board is enabled to move relative to the ball with at least a degree of spherical rotational freedom and also a degree of translational freedom in directions other than the vertical.