To explain a water flow power generation system and a sailing body that can accurately acquire information based on transmission and reception of sound waves.SOLUTION: A water flow power generation system 1 comprises: a water flow power generation device 2 for floating in water, and generating power by using a water flow; a mooring device 7 for mooring the water flow power generation device 2 in a predetermined water area; an acoustic sensor 30A and an acoustic sensor 30B arranged at positions different from each other, and for transmitting sound waves in the water, and receiving reflected waves of the sound waves; and a control device 40 for detecting the reflected waves received by the acoustic sensor 30A and the acoustic sensor 30B as sound wave signals, and acquiring information based on the sound wave signals. From the detected sound wave signals, the control device 40 identifies first sound wave signals indicating the reflected waves caused by the acoustic sensor 30A, and identifies second sound wave signals indicating the reflected waves caused by the acoustic sensor 30B.SELECTED DRAWING: Figure 3