A sink-float structure is provided with: a hollow member (2) divided into chambers (6a-6d)； a water outlet-inlet section (7) from which water flows into the hollow member (2) and into which water within the hollow member (2) flows； an air outlet-inlet section (8) from which air flows into the hollow member (2) and into which air within the hollow member (2) flows； and flow sections (10) provided between the water outlet-inlet section (7) and the air outlet-inlet section (8) and allowing water and air to flow between adjacent chambers. The water outlet-inlet section (7) is located within the hollow member (2) in the lower part thereof, and the air outlet-inlet section (8) is located within the hollow member (2) in the upper part thereof. Each of the flow sections (10) is configured in such a manner that, in adjacent chambers, an outlet-inlet section (11) for water and air is disposed on the upper side of one of the chambers, and an outlet-inlet section (12) for water and air is disposed on the lower side of the other chamber.
