NASA satellite images have confirmed the formation of a new island in Glacier Bay National Park after the Alsek Glacier completely detached from a mountain.
In southeastern Alaska, the Alsek Glacier completely broke away from Mount Prou-Knob, turning it into an isolated island. This event was captured by NASA satellite images between July 13 and August 6, 2025.
The newly formed island has an area of about 5 square kilometers and is located in the middle of the freshwater Alsek Lake in Glacier Bay National Park.
Scientists note that the Alsek Glacier has been retreating for decades: as early as the beginning of the 20th century, it was significantly larger and wrapped around the mountain on two sides. Glaciologists Austin Post and Mauri Pelto predicted the final separation of the glacier by 2020, but the process was only completed in August 2025, which was confirmed by data from the Landsat 9 satellite.
The formation of the new lake occurred gradually as meltwater accumulated in the vacated basin. In recent years, the process has accelerated due to rising temperatures in the Arctic. According to experts, similar phenomena are becoming increasingly common in the glacial regions of Alaska and the Arctic.
