An improved swim spa is described which has a tank having a head end and a foot end filled with water. A forward current is created by pumping equipment which directs the forward current from a head end of the tank, past a swimmer in the water to a foot end of the tank. The pumping equipment may be attached to a removable wall insert to which may be removed to allow easy repair and maintenance. The forward current allows the swimmer to swim in place. The width of the forward current is chosen to be at least twice its depth. A diverter at the foot end of the tank has a curved surface for redirecting the forward current toward the sidewalls and then back toward the head wall in a horizontal plane and downward and back toward the head wall in a vertical plane.