Turns out hell is actually a boiling sea floor with hydrothermal vents and lava. Or it could be a dark frozen lake which entombs people in ice, as Dante describes the ninth circle of hell. This final, deepest level of hell is reserved for traitors, betrayers and oath breakers. Also, there’s a reason why sailors used to call mermaids “sea demons”:
(via: Pinterest)
The Bible may also reference this. Revelation 21:1 — “Then I saw a new heaven and a new earth; for the first heaven and the first earth passed away, and there is no longer any sea.”