An aquatic propulsion device to be worn by a swimmer includes a first portion to be securely attached to the leg of the swimmer, which includes a bearing part having an inner face shaped so as to bear on the tibia of the swimmer and an outer face opposite to the inner face; a second portion including a first foil and a foil support, the first foil being secured to the foil support and the foil support enabling rotational articulation of the second portion relative to the first portion according to a first axis so as to make the device alternately switch from a deployed configuration into a retracted configuration.