Giantess is one of the largest and loudest geysers sometimes reaching well over 200 feet and being heard over a mile away. Unfortunately, it is relatively rare, often only erupting a handful of times per year. To complicate matters even more, it is also quite variable in the strength of its eruptions. People that have only heard about its very powerful eruptions are often disappointed if they see one of its lesser shows. They shouldn't be since even these are quite a sight but when you are expecting great height and noise, a shorter quieter eruption can be a disappointment.
Giantess is a fountain-type geyser erupting from a large pool at the summit of Geyser Hill. As would be expected with its size and close proximity to the other geysers on Geyser Hill, Giantess shows a connection to many of the geysers around it.
Eruptions, which often last a day or more, fall into three types: water, steam phase and mixed. The water type consists of bursting play that lasts about 5-10 minutes and is repeated every 30-60 minutes. As the eruption progresses, the size and duration of the water bursts decreases until the eruption finally ends. The steam phase type starts as water but changes over to a loud steam phase that can easily be heard over a mile away. The steam phase slowly diminishes and ends about 6 hours after it starts. The mixed type, which seems to be the most common in recent years, starts with water, changes to steam and then changes back to water.