The present invention provides an unmanned watercraft capable of sufficiently cooling equipment that generates a large amount of heat, capable of cooling such equipment without using energy in the watercraft, and capable of improving mean time between failures (MTBF) of a cooling device. An unmanned watercraft 1 has a cooling structure CS for cooling a central processing unit CPU1 for image recognition and a central processing unit CPU2 for control that constitute a central processing unit CPU as a heat-generating body. The cooling structure CS includes a waterproof container 7 that accommodates the heat-generating body (an insulating envelope that surrounds the heat-generating body in an electrically insulated state). The waterproof container 7 is arranged outside a submerged part 3 of the unmanned watercraft 1 so as to be in contact with water present outside the unmanned watercraft 1, the submerged part 3 being submerged in water.