[orforforof]

Bubbles will come and go, unless you're really in the white water (where you probably aren't interested in depths anyway). You'll likely have success if you make a simple software filter like "take the max depth over the past 30 seconds" with some tweaking. You'll get brief glimpses through clear water that you can capture as actual depths. People do this with sonar from jet skis, so don't despair it's a surmountable problem. (Of course those jet ski systems are big and clunky which is why your stuff is cool.)