The view of Shishaldin from False Pass is obscured by the Round Top and Isanotski volcanoes,[2] preventing direct observations of eruptions in many instances.

A very steady steam plume rises from its small summit crater which is about 500 ft (150 m) across and slightly breached along the north rim.

[2] In appearance, the volcano can vary from nearly completely white to almost all black, depending on the occurrence of ashfall deposits.

Shishaldin is one of many volcanic centers located along the 4,000 km Aleutian Arc, which stretches from Kamchatka, Russia, to mainland Alaska, United States.

[12] In addition to active volcanism, the Aleutian Arc hosts significant seismicity, with roughly 70 MW 7.0+ earthquakes since 1900.

The rupture zone of the 1957 MW 7.1 earthquake extended to the western side of Unimak Island (where Shishaldin is located).

AVO also uses satellites sensitive to thermal anomalies and volcanic plumes to monitor Shishaldin for eruptive activity.

Shishaldin produced a sub-Plinian (VEI 3) eruption on 19 April, ejecting basaltic tephra in two separate plumes which rose 9 and 16 km into the atmosphere.

The plumes deposited ash and tephra on the southern slopes of the volcano and into the Pacific Ocean, and several lahars were documented on the north flanks.

Several days of intermittent Strombolian activity followed, ash plumes again depositing material on the southern slopes of the volcano.

[7] Since the 1999 eruption, it has maintained seismic activity, typically having very low-magnitude volcanic earthquakes (most are below magnitude 1) every 1–2 minutes.

The lava flows emitted during the eruptive events have cut deep channels in the snow and ice mantle of the volcano's north slope.

After more than two years of dormancy, another eruptive cycle began and on 14 July 2023, the volcano emitted ash plumes up to 40,000 ft (12,000 m) high after several explosions at the summit.

[15] Given the straightforward nature of the climbing (Alaska Grade 1, snow up to 40 degree slope), it is possible that an earlier ascent occurred, either by native Aleuts, Russians, or other visitors.

A group climbing Shishaldin in May, 2005 set a base camp at 2,500 ft (760 m) on the east side after a four day hike and ski trip from the village of False Pass.