Extendable container for fluids with variable containment volume and dimensions

An extendable container for fluids with a variable containment volume and dimensions, the extendable container comprising:

• three or more elements that are independent and capable of relative movement among each other;
• wherein the three or more elements are formed by:
• at least one bottom element or at least one removable top lid, at least one seat element, and at least one backrest/containment element;
• wherein at least one of the three or more elements comprises at least one hole or opening to facilitate entry of water of an environment;
• wherein each of the three or more elements of the extendable container are present alone, in pairs, or in groups of three or more;
• wherein the extendable container is installed on a substrate including a floating or submersible platform for a stern deck, bow, or cover of a boat;
• and
• wherein the extendable container is capable of being hidden or concealed in said substrate where said extendable container is installed.