"A better view of the outside, at least." The Bus ascends and moves out of the ash column, with none of the sense of acceleration someone used to elevators (or non-capitalized busses, for that matter) would have expected.

Ms Frizzle takes an excited look at the volcano. Is it one of the types that tend to show up on rocky planets?

Looks like a composite volcano!

That's excellent! All volcanos are excellent, though she's rather partial to the ones on Io and Niphris III. "Ready to dive in?"

"Sure."

"Waaaaahoooo!" They turn around and dive back into the smoke cloud, and from there into the lava. It's way more viscous than water; there's almost no splash. Ms. Frizzle folds a sonar-type screen up from one of the consoles, since visibility through the lava is awful at the vast majority of wavelengths.

It looks lava-y. "There's some lava flows - not a proper volcano - that are rainbow colored."

"Ooh! Do you mean a single iridescent substance, or multiple streams of different colors?" Down down down they go.

"I don't know, I've never been and the book wasn't specific."

"Well then, perhaps when we're done here we should go find out for ourselves!" she says, staring raptly out the windshield. "Say, can you see the thermal gradients and convection currents? If you can't I can get you a pair of goggles for it."

"Ooh, I'd love a pair of goggles that did that."

"Here you are, then!" She opens a panel above her head and extracts a pair of what look like purple swim goggles. If Promise looks through them she'll be able to see the magma as sluggishly swirling currents instead of an undifferentiated mass, and on top of that the way heat diffuses through the flow. It's like watching ink spread through water, except it doesn't converge to a boring equilibrium state.

"It's beautiful!"

"Isn't it? Even something as simple as heat and rock has a lot going on under the surface." Ms. Frizzle contentedly watches an unusually hot patch force its way up.

Promise is happy to watch lava for a good long time. "Can I keep these? They'd be handy for sorcery."

"Of course! I have ones that let you see sound waves, too, would you like a combined pair?"

"Sure!"

Then she can get a second pair of lenses that add colorful ripples over any vibration source, with amplitude and frequency indicated by color and density. It stacks pretty intuitively with the heat vision.

"I love it."

"Glad to hear it! Shall we try finding out when this volcano formed?"

"Sure."

They start jumping back in time a bunch!

And they can watch lava erupting gloriously from the mossy ground in a huge gout.

This is hilarious. And best viewed through a glass-bottomed vehicle, which the Bus now is.

Neat.

Ms Frizzle has all sorts of stuff to say about the implications of an eruption of lava with no ash and without lava being flung hundreds of feet in the air. Also about how this is going to produce some very nice obsidian when it cools.