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.
|Giantess has at least two types of eruptions; the first seem to come out of nowhere, unexpected and with no noted signs of impending eruption. Therefore, luck is the best way to catch it from the start. However, a six-foot boil usually indicates the start of the eruption.
The other way is a slow buildup to an eruption where the pool grows ever increasing hotter as boiling increases in frequency. What to watch for in this case is frequent (every two to three minutes) boiling episodes and rim boiling, especially rim boiling on the north side of the pool, but more importantly, those “north rim boils” must pump out water onto the platform to reduce the static head of the pool.
Giantess is very sensitive to wind under these conditions and boiling may stop completely as the wind increases, and then resume again when the wind dies down. An eruption of Beehive Geyser has also caused the boiling to stop for a short time.
These periods of increase heat may last a day, up to several days, until it erupts, or the “Hot Period” ends. Once again, the eruption usully begins with a six foot boil from the center of the pool.