A Lush, New Island Has Formed Within Alsek Lake In Alaska's Glacier Bay National Park

As the ice around Alaska's Glacier Bay melts, the geography of the national park named for it is being reshaped in real time. One dramatic example is a once-connected hillside that now stands alone in Alsek Lake, transformed into its own island. Long surrounded by the Alsek Glacier, Prow Knob became disconnected over the summer of 2025, as the glacier retreated, or melted, and Alsek Lake washed in. Now, Prow Knob stands as a lush, 2-square-mile island.

The change was spotted in satellite images from NASA Earth Observatory. Published photos show the shift from 1984, when Prow Knob was still connected to the terminus of Alsek Glacier, to 2025, where it stands alone, rising over 1,000 feet out of the lake. In the early 1900s, the glacier reached a whole 3 miles to the west of this new island, according to glaciologist Mauri Pelto. The lake itself, fed by the Alsek River and flowing out into Dry Bay, has more than doubled in size since 1981 due to glacial melt. While visitors can cruise to Glacier Bay National Park, itineraries don't include Dry Bay or Alsek Lake, meaning there's only one real way to get a glimpse of this new island.

The only way to see Prow Knob up close is by rafting down the Alsek River, one of North America's most remote and spectacular wilderness routes. The multi-day journey begins in Canada and winds through deep valleys carved by ice, passing glaciers, towering peaks, and floating icebergs, as well as a whole lot of grizzly bears. Toward the end of the trip, rafters spill into Alsek Lake, where the new island sticks out of the blue-gray water. It's a challenging expedition that requires experience, permits, and a helicopter portage (yes, really!).

For a more accessible taste of the same dramatic scenery, visit Glacier Bay National Park by cruise ship. From the deck, you'll watch glaciers calving into the sea and spot wildlife, like brown bears and humpback whales, from a safe distance. If you really want to get up close to incredible glaciers, consider a kayaking trip, either for one day or as part of a multi-day adventure. Glacier Bay is one of several national parks that are free to visit year-round, though with no roads connecting the park to the outside, your only way in is by boat or plane. Most visitors to Glacier Bay will never get to see Prow Knob, but the map is changing throughout the park, as retreating glaciers form new landscapes.