Water quality monitoring. Communicate back to the surface with ultrasonic pulses.
And in case people think ultrasonic signaling isn’t a real thing, it very much is. In the oil and gas industry, it’s how measurements taken while drilling a hole are sent back to the surface through the drilling mud.
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And in case people think ultrasonic signaling isn’t a real thing, it very much is. In the oil and gas industry, it’s how measurements taken while drilling a hole are sent back to the surface through the drilling mud.