The Fountains were Sealed with Magma

Can we make the case that the phrase "When He strengthened the fountains of the deep," means "sealed shut with lava or magma?" We'll need to look at other passages where the word translated as strengthened occurs.

Mist or Steam?

The context of the mist that went up is important. It's part of the narrative of the week of creation when the fountains of the great deep had to be sealed after the deep had drained through them into the interior of the Earth.

The Great Deep

The deep and the great deep are both translated from the same Hebrew word, tehom. The difference signifies a transition from the deep where Earth was created to when the great deep is in the interior of the Earth.

Tehom

Lower Noachian

We (that's me and the Holy spirit) make a contextual connection between tehom and sheol because they're both used to refer to the underworld realm of the dead, also known as the grave.