robtillaart:
idea:
As water is transparent for light you could lay a mirror on the bottom and have a laser pointing at it and measure reflection?
A TSL235R light intensity sensor might be able to detect a shadow ?
I wish! Unfortunately, I'm at a gym pool, so putting together a mirror and laser setup 10 feet down each day probably won't fly. I also have to share a lane on some occasions, so I'm not sure motion detection would be a good fit either. This is why I've been thinking there would have to be a sensor that I am carrying.
Is there any sort of setup where two small sensors would be able to identify their proximity to each other? (or, if they're simply within a certain proximity in general)