Abstract: A skimmer comprising two main, nested components: a skim vat (1) supported by floats (3) and arranged to float beneath the surface (5) of a sheet of liquid; and a spillway (6) supported by floats (7) and free to move telescopically with respect to the skim vat. Liquid is extracted from the bottom of the skim vat (1), thereby lowering the surface (8) of the liquid therein until the spillway (6) which floats with respect to the inside liquid surface (8) has moved far enough down for the rate of flow of surface liquid into the skimmer over the rim of the spillway, to match the rate of extraction via the pipe (4). Two O-ring seals (9 and 11) prevent liquid from escaping from the inside of the skimmer while allowing the nested components to move relative to each other. The skimmer is particularly intended for removing surface pollution from stretches of water.