A seat for a watercraft provides a separately adjustable thigh support and back support. The seat includes a pelvis support and a separately positionable thigh support pivotally mounted on the pelvis support. An adjustable back support includes a post pivotally mounted to the pelvis support and a backrest that moves vertically on the post. Means are provided for adjusting and setting the thigh support and back support at desired positions for optimal support and comfort. Preferably, a person can adjust the seat while fully seated in the seat.