Abstract: An apparatus for the continuous and direct measurement of the temperature of the upper superficial layer of the surface of the sea or other water surface, which apparatus comprises a central floating member and at least one arm connecting the central member to at least one peripheral floating element, the or each arm containing a thermal collector for transmitting heat to at least one temperature detector carried by the apparatus, wherein the central member and the peripheral floating element are adapted to maintain the apparatus on the water surface while at least a part of the or each arm is in contact with and senses the upper superficial layer of the water, and wherein electrical means are provided in the apparatus for the storage and/or transmission of temperature data from the or each temperature detector.