Abstract: A collapsible dome includes two or more arches of larger radius than half of the diameter of the pool which are therefore lower and provide a consequently lower structure, preferably of arcuated shape. Arches are pivotably attached on one end to the first support base, mounted to the pool's edge, and on the other to the second support base. Second support base is slidably hung upon a support guide bar which is mounted on the pool's edge with one end opposite the first support base and a membrane cover attached to each arch and tensioned after set up to the pool's edge. While the membrane is not fastened to the pool's edge, one side of the collapsible dome can easily be shifted along the support guide bar. Before collapsing the dome, the second support base should be shifted along the support guide bar in the appropriate direction to decrease the circumference between the first and second support bases.