Abstract: A fluid tight enclosure suitable for use as a swimming pool positioned either above or below ground level, or for relining an existing pool. The enclosure comprises a plurality of waterproof panels forming the side walls and floor, the panels being sealably interconnected by a structure which includes a resilient elastomeric sealing member bridging the adjacent panels and sealably contacting the front faces thereof. A relatively rigid plastic cover member overlies the sealing member, and in one embodiment of the disclosed invention, a relatively rigid plastic base member is positioned to underlie the sealing member, the base member including an upwardly directed flange adapted to operatively engage a conforming portion of the cover member to secure the cover member in it position overlying the sealing member.