OBJECTIVE: A device that floats on the water's surface and measures the depth. If any changes occur in the depth, it sends a report to a remote receiver.
MY RESEARCH: I have considered the following sensors but they don't seem to be effective:
- IR won't work because water absorbs red light.
- Ultrasonic: I can't find one that works underwater.
- I also read a thread: Underwater distance measurement/Sensing however, I don't know if I can implement that.
What sensor can I use for this purpose?