Overview

• Landsat 9 imagery indicates the final ice separation occurred between July 13 and August 6, 2025.
• Prow Knob spans roughly 2 square miles (about 5 square kilometers) with a high point just over 1,000 feet.
• Alsek Lake has expanded from about 45 to 75 square kilometers since 1984, with 2024 images showing bluer water consistent with less fine sediment.
• Glaciologist Mauri S. Pelto monitored the site monthly and expected the detachment earlier, noting that new islands of this size from glacier retreat are rare.
• Researchers caution that retreat increases risks such as calving, landslides and seiche waves, and the evolving area is under active scientific and park oversight.