Tedin, I've heard that lake story before. It's been a long time since I thought of it, though. I remember it as being carbon dioxide that developed on the bed of the lake and erupted during the night, killing an entire village. I guess it's happened more than once. Makes one wonder about something like that happening at Crater Lake!
Unless your son gets an overwhelming desire to climb a mountain, I doubt he'll be going too far up on Hood. Even if he did decide to climb, people would undoubtedly steer him toward one of the tamer peaks. My friend and his son were both very experienced mountaineers. Otherwise, they wouldn't have gone during the spring, because Hood is VERY dangerous at that time of year. It's impossible to predict what the mountain will do at any given time.
I was never what one would call a mountain climber, just did a lot of hiking. I don't like being out on the glaciers. I turn into a very delicate hothouse flower -- a total wuss -- at the first mention that there might be the possibility I could fall into a crevasse.