Open pool forming a reservoir for liquid, especially swimming pool, of the out-of-ground type with a flexible wall (2) and an inflatable tubular chamber (3) constituting a floating ring which defines the opening of the pool, characterized in that, in the service position of the pool (1), the upper peripheral region (5) of the flexible wall (2) adjoining the tubular chamber (3) is inclined, relative to the remaining underlying part of the wall, towards the inside of the pool, by virtue of which the upper peripheral region (5) forms a frustoconical reentrant rim underlying the tubular chamber (3) and capable of holding the tubular chamber (3) up when the latter is subjected to a downwards force.

A variable size, portable above-the-ground swimming pool comprising a frame portion having a flexible liner portion attached thereto. The frame portion includes a plurality of first wall members which are of a first length. Attached to and extending between the top ends of the first wall members are a plurality of rim members. The liner portion includes an upper rim which defines a plurality of horizontally oriented rim sleeves sized to slidably receive respective ones of the rim members. Extending downwardly from the upper rim is a sidewall which defines inner and outer surfaces. Disposed on the outer surface of the sidewall are a plurality of vertically oriented wall sleeves which are sized to slidably receive respective ones of the first wall members, while attached to the sidewall is a floor. The sidewall is of a first height, and is selectively collapsible to a second height which is less than the first height. Additionally, the first wall members are selectively replaceable with a plurality of second wall members which are of a second length less than the first length for purposes of reducing the size of the pool when the sidewall is collapsed to the second height.