Sneak down underwater with new controls

So about the new controls.. they're pretty good except you cant sneak underwater..

how am i supposed to survived it i get sucked down by a magma block under the water? 
the d-pad control can sneak underwater but why not the new controls? I know this is just a bug but please.. this can be useful to me so i can use it to hide my nametag on water (mostly when a mon approach)

in MCPE