Marshmallows and volcanos do not mix!

So sayeth the USGS.

Read and smile.

Nobody needs a s’more that much.

You just know that some people are going to se that as a challenge, right?
Besides, who can get close enough to the actual vent? Wouldn’t it be more reasonable to ask if you could roast marshmallows 9or hot dogs, or whatever) over a portion of the lava flow? Less worry about VOG and hydrogen sulfide gas.

Aaaand, of course, someone’s already done it. Using artificial lava, so it avoids those questions about nasty gases:

But here';s cooking on an actual lava flow: There are actually quite a few sites with people cooking on lava flows out there

You can probably toast your marshmallows at this resort – they routinely use volcanic heat for cooking

Yep. But just because it’s done doesn’t mean it’s safe.

Marshmellows are mostly sugars and corn syrup. Emissions from volcanic eruptions often release sulfuric acid.

Sulfuric Acid + Sugar =

No Smore’s for you!

Again, there are people who would try doing this Just Because this reaction was a possibility. (I suspect you’d need to combine a LOT more sulfuric acid with the marshmallow than you’d get from the gas coming through the vent in order to se anything at all like this)

It occurs to me that the presence of sulfuric acid by itself ought not to be a deterrent in cooking over volcanic vents. Any good chef, like any good artist, works with his materials to exploit their possibilities and advantages, rather than against them. If making s’mores is contraindicated by bad reactions, then that’s just a sign that you’re trying to use the wrong ingredients in this situation.

It turns out that sulfur is a much-neglected and essential nutrient:

So what can you cook that takes advantage of sulfur?

So there you go! You can cook your eggs over volcanoes. Or garlic-laden fare. And extra sulfur you pick up will only be adding nutritious sulfur.