Abstract: Apparatus for skimming matter such as oil, scum, and the like floating on water in rivers, lakes, oceans, water-tanks, settling-tanks. The apparatus is adapted to float on the water and comprises a vessel having a main floatable body with at least one inlet opening provided in the sidewall thereof and with matter storage container means in fluid communication with the sidewall inlet opening. A floatable gate means is provided externallly on each sidewall inlet opening of the main body in slidably supported relationship to the latter and is adapted to float on the surface of the body of water outside the main floatable body. Each gate means includes a vertical gate plate externally disposed slidably on the inlet opening sidewall of the main floatable body, the gate plate having an inlet opening therein adapted to be at least partially aligned with the corresponding sidewall inlet opening, at which time only, the floating matter can enter the main floatable body through the at least partially aligned openings.