I've never heard of anyone doing it, but I see no reason it would be a problem, other than battery duration. With the 5870mah battery I wouldn't go much farther than 500M down, in fear of having enough battery to climb back up. Keep in mind the estimating gauge in Go4 likely doesn't account for heavy power draws to climb back up to the launch altitude, just like it doesn't account for wind. So I'd make sure to turn around at about 70% the first time you try that mission if you're 500M down.