Matthew 18:6

but whoever offends one of these little ones that believe in me, it would be better for him that a millstone should be hung to his neck, and that he should be plunged into the depths of the sea.

Revelation 18:21

And a mighty angel took up a stone like a great millstone, and cast it into the sea, saying, Thus with violence shall Babylon the great city be cast down, and shall be found no more.

Treasury of Scripture Knowledge

Summary

The depths have covered them: they sank into the bottom as a stone.

Depths

Bible References

Depths

Matthew 18:6
but whoever offends one of these little ones that believe in me, it would be better for him that a millstone should be hung to his neck, and that he should be plunged into the depths of the sea.

They

Revelation 18:21
And a mighty angel took up a stone like a great millstone, and cast it into the sea, saying, Thus with violence shall Babylon the great city be cast down, and shall be found no more.