Abstract: An adjustable sun lounge for a performance or pleasure boat. The sun lounge converts from a seating configuration into a sunbathing configuration. The sun lounge generally includes a backrest which is movable via a double-pivot hinge and guided by a guide arm from an upright position to a substantially horizontal position. The sun lounge also includes a sunpad and a center cushion movable via a single-pivot hinge from an inclined position to a substantially horizontal position. When the backrest is in the substantially horizontal position and the center cushion is in the substantially horizontal position, the sun lounge is substantially horizontal and flat to accommodate a sunbathing person stretched out thereon. In the upright position, the backrest forms part of a seat structure which may be used when sunbathing is not desired, for example, while the boat is moving.