The 8 km (5 miles) round trip between Fairy Falls trailhead in the Rabbit Creek Group and Fairy Falls is a very popular hike in Yellowstone. From Fairy Falls the trail continues just 1.1 km (0.7 miles) in northwestern direction to the Imperial Group. This small thermal group comprises only two features, Imperial Geyser and Spray Geyser. Nevertheless, both are highly active and visually pleasing, so it's well worth a visit.
The first thermal feature you come across, Spray Geyser, lies at some distance to the trail beyond Imperial Geyser's runoff. Over the past decades Spray Geyser's intervals, which have always been in the range of less than one minute, decreased more and more and so did its eruption heights. So today it nearly acts as a perpetual spouter and plays from different vents no more than 2 m (6 feet) high.
There is some evidence that Imperial Geyser's spouting activity emerged not until the late 1920's. The mode of Imperial's play varied over the years considerably, from longer intervals and strong eruptions up to 24 m (80 feet) height to near-dormancy. There has also been an interchange of the vent, so the currently active vent is called "New Imperial Geyser". New Imperial plays up to 15 m (50 feet) high at intervals in the range of seconds.