its a free volcano fire show! kinda gets crowded at times, but in vegas there aren't a huge number of free things to do.
its pretty amazing to watching, you can feel the heat from the flames. the music is cheesy, like some natives are dancing around the fire about to sacrifice a virgin type thing.
watch it once, cause it won't suck. You'll be amused, entertained almost for a few minutes and then be along your way. Makes me wanna roast some marshmallows afterward.
There is a tram between the mirage and treasure island if you're too lazy to walk.