an expendable oceanographic sensor apparatus is deployed from an airplane or a ship to make oceanographic observations in a profile of the surface - to - ocean floor , while deployed on the floor , and then a second profile when returning to the ocean surface . the device then records surface conditions until on - board batteries fail . all data collected is stored and then transmitted from the surface to either a satellite or other receiving station . the apparatus is provided with an anchor that causes descent to the ocean floor and then permits ascent when the anchor is released . anchor release is predetermined by the occurrence of a pre - programmed event .