Neltharion takes a rather nice and rather steamy swim through magma tubes.
I just imagine what happens when Squishy does his job and how he preforms his job.
I know, in real life this would be a bit difficult...to see and to do...considering the density of molten rock compared to a living being, but this is the Earth Warder we're talking about. He swims through molten rock like a blue whale swims through sea water.
Considering how fat Nel is, that isn't far off.
But I do add some realism to this idea. Neltharion navigates through magma using seismic vibrations and sound waves, the Earth Warder version of sonar. He does not use any sight at all. In fact, he keeps his eyes closed when he does it.
Neltharion/Deathwing © Blizzard (his beard is mine)