It seems Black Diamond Pool is active again – there was a report of a big eruption in that area from a visitor. It sounds like it was a muddy one with rocks and other debris tossed out. The first report came in on 27 Oct 2011 and was confirmed by someone familiar with the area. The photo above shows how it looked a little over a month ago. Now it sounds as though the water level has risen and is all one murky pool. Just keep in mind, though, that the signs on the boardwalk are incorrect and should, at some point, be switched.
Black Diamond was also active in May 2009 – information on that witnessed eruption (by a group of geologists including the YNP Geologist) is in the June 2009 issue of the Sput (Vol. 23, No. 3).
If, by chance, you happen to be in the Park this last week of this summer season, it might be worth a stop at Biscuit Basin to see how things look. For comparisons, here are some more photos taken on 28 Sept 2011.
When you first come over the bridge, you’ll see Black Opal Pool. In the distance you can see “Salt and Pepper” – an informal name given to a relatively new thermal feature that is now a continual spouter.