PROBLEM TO BE SOLVED: To make it possible for an underwater vehicle itself to select a floating position without obstacles.SOLUTION: An underwater vehicle 1 comprises a floating-position selector 8 that includes a floating position controller 9 and a planned-floating-position-setting storage unit 10. In a case of floating the underwater vehicle 1, the floating position controller 9 calls position information on a planned floating position 11 from the planned-floating-position-setting storage unit 10, and controls a sonar 7 of the underwater vehicle 1 to scan the planned floating position 11 and a peripheral region 12 of the planned floating position 11. On the basis of a result of scanning, water level depths of the planned floating position 11 and the peripheral region 12 are averaged in time and plane space, and the planned floating position 11 is selected as an actual floating position if averages of the water level depths of the planned floating position 11 and the peripheral region 12 are not positive an
