Tutorial/Fractured Ice Surfaces...

In Snezhnaya, some icy surfaces can be smashed by an attack or applied weight, creating an ice grotto. When this happens, everything on the ice surface will fall inside... and will immediately be affected by the extreme cold down there.

But do not worry, a grotto like this will eventually refreeze and ice over. But if this starts happening while you are still inside, better get out while you can.