I visited White Island / Whakaari when I was in New Zealand this March

Although it took a surprisingly long time to be recognised as such historically, it is very definitely an active volcano: the day I went, the green acidic crater lake was steaming enough that I didn't even bother to try to to get close enough to see it as even with the supplied gas masks, it was stinging my nose and throat and it turned out that you couldn't actually see the lake anyway.

The place has some monitoring stations looking at things like the ground rising and part of the tour is looking at some of them. But normally, it's the sea condition that means you can't go by boat, and I wonder if the weather they've been having recently - lots of storms - meant that there was commercial pressure to have the trips despite the warnings of increased activity since July.*

You also see the remains of the sulphur mining station that was wiped out 105 years ago - the only survivor was the cat - so this isn't the first time the volcano has killed people.

Even somewhere like New Zealand that has several active volcanos, that you're visiting the most active of them is its appeal...

* Some of the coverage here has made it sound like the warnings were very recent, but it's been months since the alert level changed