So, I decided to play Minecraft again. First few nights was ok, but sometimes when I turn off the screen while ingame and turn it back on I get greeted by this wonderful landscape. I tried to find exactly where all that mess is coming from and it turns out it's a glitched "drowned" model. Re-loading the world seems to fix it. 

My device is Xiaomi Redmi Note 5.

My Minecraft version is 1.5.0.10, but it isn't letting me put that in.

P. S. Sorry for horrible screenshot resolution, I have a recording of the problem that I uploaded to Google photos but it isn't allowing me to download it so I just screenshoted it.