Now, modern multi-beam echosounders produce tens of thousands of globally positioned depth measurements every second over wide swathes, 3D imaging sonar allow operations in zero visibility, we can position multiple moving or fixed objects underwater, and communicate with underwater vehicles and sensors using acoustic modems. It is, however, important to note that accurate and timely measurements of the sound speed structure through the water column are critical to any acoustic technology and this presents its own set of challenges as we move into the autonomous era.
Our understanding of the structure of the world’s oceans, and the interactions between the atmosphere and bodies of water has been greatly assisted by the ability to make readings of temperature, salinity, sound speed and biogeochemical parameters at depth using sensors that can be fitted to moving vessels, underway winches, autonomous underwater vehicles, and even diving marine predators (2).