I actually haven't. There's only one island that has an active volcano and I've only visited it a couple times. Also, active with flowing lava is still pretty rare, usually it just makes smoke and sometimes "vog" (volcanic ash clouds). I've experienced vog when the winds come from the Big Island and sweep NW towards Oahu. I was jogging one day and got him with a bunch of soot in my nose. I don't think it was a net gain healthwise from jogging that day... Years later I understood why all the Kenyan marathon runners refused to participate in the Beijing Olympics because of the pollution.