Grand is a fountain-type geyser. Its interval is usually around 6 to 15 hours (the average has been about 7 to 8 hours for the past two years). Its height is about 150 to 180 feet (45 to 55 meters) and its duration is about 9-12 minutes. It will sometimes stop after about 8 to 9 minutes and then restart after a minute or so. This second “burst” and any subsequent bursts are often among the tallest if not the tallest of the eruption. Be sure to wait to see if there is a second burst.
The Grand Geyser is pretty unpredictable concerning the intervals. It took a lot of patience and long waiting time to see the eruption of “his Majesty”, but worth the patience. I was petrified by its beauty. It stopped for minuts when the Castle Geyser started to erupt. While running like crazy to admire the Castle Geyser, the Grand had a phenomenal second burst. I dropped everything to catch it and here it is. You can see a few tiny little silhouets still close to the Grand and one photographer surprised in the middle of his run, just like me ;)))