Kirk here. I haven’t seen this with my own eyes yet but I’ve seen several posts like this one that show emerald green water in the volcano. To be honest, though, I’m not exactly sure where this photo was taken. It doesn’t seem to be the part of the volcano that belches steam. The person who posted this to Twitter wrote that the color (and perhaps the presence of the water itself?) was a result of the recent rain. Anybody been there recently?