Lord of the Rings, rated PGP

[Lalwendë]

(It would be weird book-wise too) Frodo and Sam were mere meters away from the boiling lava on Mount Doom. My Dad says they shouldn't have been able to survive.

Your dad could be right there, certainly in terms of the films. The overwhelming amount of sulphur in the air would have choked them to death. And there is the volcanic phenomenon known as pyroclastic flow - when gasses are released under tremendous pressure and overwhelm all in their path, even eagles wouldn't have been able to withstand such forces.