Abstract: An expandable flooring system for a pontoon boat includes a center floor and at least one outer floor. The outer floor is configured to hinge upwards about an edge of the center floor. At least one outrigger is extendable from a corresponding slide track under the center floor. The outrigger is configured to slide under the center floor when the outer floor is hinged upward, and slide out from the center floor for supporting the outer floor when it is hinged down and next to the center floor. A railing system surrounds the periphery of the flooring system and is secured together for providing rigidity to the flooring system.