Abstract: A subsea measurement apparatus (104) is configured to be immersed, when in use, in water, and comprises a sensor, a communications module, and a processing resource operably coupled to the sensor and the communications module. The sensor is configured to measure a property of a medium and the processing resource is configured to provide a first execution environment (122) and a second execution environment (124) independent from the first execution environment (122). The first execution environment (122) is configured to execute device firmware (128) that cooperates with the sensor to generate, when in use, measurement data. The second execution environment (124) is configured to receive and execute a user-defined application (130).

Abstract: An underwater acoustic receiver apparatus (100) comprises an acoustic reflector (102, 104, 106, 108) and an acoustic device (110, 114, 116, 118) aimed at the acoustic reflector (102, 104, 106, 108). The acoustic reflector (102, 104, 106, 108) is disposed at a predetermined distance and orientation relative to the acoustic device (110, 114, 116, 118).

Abstract: An aquatic time synchronisation system includes an aquatic first acoustic communications apparatus capable of communicating acoustically with a dynamic aquatic second acoustic communications apparatus. The first acoustic communications apparatus includes a first time source and the second acoustic communications apparatus includes a second time source. The first acoustic communications apparatus is arranged to communicate a first acoustic signal to the second acoustic communications apparatus and the second acoustic communications apparatus is arranged to communicate a second acoustic signal to the first acoustic communications apparatus in reply to the first acoustic signal. The first acoustic communications apparatus is arranged to use data associated with the first and second acoustic signals in order to determine a time offset between the first and second time sources.

Abstract: Acoustic devices, attached to fishing nets, reduce or avoid by-catch of marine animals during fishing operations. The acoustic devices emit a deterrent signal to a particular marine animal on actuation by the approach of the animal. At least one of the devices is an active device that detects marine animal emitted stimuli and responds with a suitable response emission.