Swimming pool with a movable bottom, the swimming pool comprising: - side walls and a movable platform that together define the bathing volume of the swimming pool, the platform being capable of passing from at least one low submerged position to a raised position (Pf) in the open air, closing the bathing volume, - a system for actuating (4, 5) said movable platform in order to raise or lower same, - a peripheral flow conduit, arranged at the periphery of the bathing volume and said side walls, said flow conduit having an upper mouth system and a lower mouth system communicating with the bathing volume so as to make it possible that, under the action of the movable platform, the water flows through said flow conduit, on either side of the movable platform, from the upper mouth system to the lower mouth system during the raising of said movable platform, and from the lower mouth system to the upper mouth system during the lowering of said movable platform, characterised in that said swimming pool is an overflow pool comprising: - a main water tank containing the water of the overflowing bathing volume, receiving said side walls, the flow conduit and the movable platform, - one or more secondary tanks for collecting the overflowing water, with a buffer function, called buffer tanks, - a pump system linking the buffer tanks and continuously supplying the overflowing bathing volume from the water from the buffer tanks, and wherein said swimming pool comprising a water collection system, extending at the periphery of the bathing volume and suitable for collecting the water overflowing at the periphery of the bathing volume, and wherein said overflowing water collection system is at least partially movable, being capable of passing: - from a low position for which the water collection system, on the one hand, constitutes an overflow defining the height of the overflow, ensuring the receiving of water when the swimming pool functions as an overflow, the movable platform thus static in at least one submerged low position, in a first state of said collection system enabling the flow of the collected water to the buffer tank(s), and on the other hand, constitutes a trampling substantially at the level of the movable platform thus in a raised position (Pf) and closing the bathing volume, in particular in a second state of said collection system, - to a high position, situated above the level of the raised position (Pf) and of closing the movable platform, high position for which the water collection system constitutes a peripheral anti-overflow barrier during movements to raise or lower the movable platform, in a third state of said collection system which thus constitutes the upper mouth system of the flow circuit by which the water enters during the raising of the movable platform, or the water emerges during the lowering of the movable platform. - side walls and a movable platform that together define the bathing volume of the swimming pool, the platform being capable of passing from at least one low submerged position to a raised position (Pf) in the open air, closing the bathing volume, - a system for actuating (4, 5) said movable platform in order to raise or lower same, - a peripheral flow conduit, arranged at the periphery of the bathing volume and said side walls, said flow conduit having an upper mouth system and a lower mouth system communicating with the bathing volume so as to make it possible that, under the action of the movable platform, the water flows through said flow conduit, on either side of the movable platform, from the upper mouth system to the lower mouth system during the raising of said movable platform, and from the lower mouth system to the upper mouth system during the lowering of said movable platform, - a main water tank containing the water of the overflowing bathing volume, receiving said side walls, the flow conduit and the movable platform, - one or more secondary tanks for collecting the overflowing water, with a buffer function, called buffer tanks, - a pump system linking the buffer tanks and continuously supplying the overflowing bathing volume from the water from the buffer tanks, - from a low position for which the water collection system, on the one hand, constitutes an overflow defining the height of the overflow, ensuring the receiving of water when the swimming pool functions as an overflow, the movable platform thus static in at least one submerged low position, in a first state of said collection system enabling the flow of the collected water to the buffer tank(s), and on the other hand, constitutes a trampling substantially at the level of the movable platform thus in a raised position (Pf) and closing the bathing volume, in particular in a second state of said collection system, - to a high position, situated above the level of the raised position (Pf) and of closing the movable platform, high position for which the water collection system constitutes a peripheral anti-overflow barrier during movements to raise or lower the movable platform, in a third state of said collection system which thus constitutes the upper mouth system of the flow circuit by which the water enters during the raising of the movable platform, or the water emerges during the lowering of the movable platform.