I'm using this in my next Zork clone ;)
I was young and stayed in the local backpacker which had a naturally-warm water pool!
As you approach the city, you feel a very strong smell of sulphur (a smell described usually as rotten eggs), but as you stay in the town you more or less get used to the smell and stop feeling it... it's not as bad as it sounds.
Highly recommend a visit if you're around Australia or the South Pacific.
One day I want to visit Iceland as well, it looks amazing.
What amazed me was the absolute sheer about of heat generated from that one TINY little patch. Like, as intense as standing in front of a pizza oven going at full blast. I could stand about ~15 seconds of it once I exposed the molten part, and then I had to step away. Overall in the area it was warm - mostly because it was Hawaii and hot out! - but also because of general ambient warmth. But it was just that - warmth.
But when I exposed that piece of molten lava - that was HEAT.
Although the soles of my sneakers were semi-melted by the end of the day. I blame my sneakers more than anything (cheap, lowish melting point rubber), but still....
A few years ago, I visited the Masaya Volcano in Nicaragua. It wasn't one you could get super close to, and the photos are a bit underwhelming, but it was still very impressive to see in person. This is what you can expect to see as a tourist: https://hotelplazacolon.com/wp-content/uploads/2017/10/Masay...
The heat coming off of the volcano was significant, but not exactly overwhelming. The sulfur smell was overwhelming (apparently Masaya emits a lot of sulfur dioxide), and there were restrictions as the length of time tourists could stay at the volcano due to the gasses. There were signs all over, posted in English and Spanish warning about the health effects of the gasses emitted.
Definitely exercise caution when parading around Iceland: nobody is going to stop you from walking yourself into something hot/dangerous.