A readily assemblable and collapsible floating or standing dock is constructed of a plurality of transversely-extending elongate aluminum deck forming members releasably connected, through a simple interlocking fastening arrangement, to parallel elongate aluminum side rail members provided at each longitudinal side of the dock. Aluminum end rails are releasably interconnected between the side rail members to provide a rigid frame structure. An aluminum bumper rail extends along each longitudinal side of the dock with portions overlying the ends of the deck-forming members and portions releasably connected to the elongate aluminum side rail members.