You aren't supposed to be able to dive at all without a certification. So the term "uncertified divers" makes zero sense. So, if you're "uncertified" and you s

You aren't supposed to be able to dive at all without a certification. So the term "uncertified divers" makes zero sense. So, if you're "uncertified" and you somehow managed to get yourself a filled air tank, then my point still stands: you can go down to however deep you want. And the basic open water certification is not much more than a rubber stamp. Anyone can get it as long as they pay their $100 to PADI or whoever else.