We Have Returned!
Ein and the three were ejected from the dungeon moments before its destruction. Imagining if they were late for a few seconds more and didn't kill the dungeon master in time leaves them feeling a little scared.
But before they could even sigh in relief, they just saw Ein, holding the heavy Mjolnir in his hands, sink straight down. The water was deep too, given that the area they were thrown into was after a shelf break under the ocean floor. In just seconds, he was already hundreds of meters deep.
"...!"
Ein may be a demigod himself, but he's still a mortal. Not breathing for a long time would be fatal for him, not to mention the effect of the sudden increase in water pressure as he rapidly sank. Adding to the fact that Mjolnir doesn't want to get out of his grip, he can't help but curse his bad luck.