Penta Geyser

Penta Geyser is a small cone-type geyser in the Upper Geyser Basin. It is located in the Sawmill Complex with geysers such as Sawmill Geyser and Spasmodic Geyser. Penta was named for its five vents and was once known as the Handsaw.

Eruption Pattern
Penta erupts from a small cone only a few feet from the boardwalk. Due to its location in the Sawmill Complex, Penta has a very close relation to the activity of Sawmill and the other geysers in the area. Penta's eruptions usually begin when the water levels in the complex are rising. This usually occurs after Spasmodic, and sometimes Tardy Geyser's eruptions begin. Before an eruption, water pools up near Penta. It can flow down toward Sawmill. Even very late in these stages, Sawmill can begin to erupt and cut off Penta, causing it to drain without an eruption. Penta Geyser usually erupts with Spasmodic, and ends a few minutes after Spasmodic stops. The eruptions are more common when the Sawmill Complex is in "Penta-Churn" mode.

Usually it is a fairly infrequent performer but during the Penta-Churn mode, it can be seen as often as two or more times per day. Eruptions consist of jetting from the main vent up to 25 feet tall and splashing and jetting from the other vents to as much as four feet. Penta's durations range from 30 minutes to over two hours.

Penta has a second type of eruption, which consists mainly of steam and small amount of water. These "steam-phase" eruptions are fairly rare. They often occur during a deep drain and usually last less than 10 minutes.

A 2015 video of Penta erupting can be found here.

History
Penta geyser erupted fairly frequently between 2013 and 2017, with intervals ranging from 20 minutes to a few days. It should be noted that data collection is inconsistent in winter months, meaning some intervals between reported eruptions may not accurately reflect actual eruptions.[citation needed]

Current Activity
The last known eruption of Penta Geyser was at 0855 on January 4, 2017. Since then, observations have been made periodically regarding the water level, steaming, and bacterial growth.

A comment from rbwhitaker on GeyserTimes.org noted:

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''Water is high enough that the two bottom vents' pools have merged into one. Water is hot and steaming, but no boiling in any of the vents. I can see water in one of the cone vents, and it's rising and falling maybe an inch or two every second or two.'' =====