A multi-position seat for a kayak or other watercraft includes a seat frame and a pivotally connected back support. A pair of side elevation adjusters engages the seat frame on its lateral sides. Each adjuster includes a thumbwheel adjuster within an elevator traveler within a side frame, the traveler engaging a threaded shaft that is held in a fixed rotational position. The frame includes a tunnel structure associated with a front cross member. A strap passes through the tunnel, exits at lateral sides of the front cross member, and connects to lateral sides of the pivotally connected back support. The strap is user-adjustable in length so that the angle of the back to the seat is adjustable. The seat is thereby adjustable in angle front-to-back, can be canted left-to-right, changed in elevation, and the back support can be adjusted in angle and elevation.