Abstract: A moving floor (1) which is to be installed in a basin (3) of a swimming pool (2) in order to be placed either in a lower position in which swimming is possible, or in an upper position in which it covers the basin (3). The moving floor is provided with compartments (7, 8, 9) which on the one hand allow the moving floor (1) to be made to float horizontally on the water (6) when the compartments (7, 8, 9) are filled with air, and on the other hand allow the moving floor (1) to be made to sink when the compartments (7, 8, 9) are filled with water in order to place it at the bottom of the basin. Controlled elements for managing the quantity of air and water present in the compartments (7, 8, 9) are also provided.