haha i'm a search and rescue diver and often dive the mississippi river (literally zero visibility) searching for bodies, weapons, etc., so I'm pretty familiar with what's involved in this type of situation. i wasn't recommending that some kid that just got his open water certification go diving for this go pro as that's be pretty dangerous.
you are correct in that you'd do this as a solo dive. However, you'd want to be tethered to a safety line with a line handler/backup diver on shore. it'd likely be black water and you'd have to "dive" completely by feel. and by "dive" I mean you load your weights about 3x what you typically use and basically lay on the bottom and crab crawl your search pattern feeling everything on the bottom by hand as these are your "eyes" in black water.