As glaciers retreat at alarming rates, a near-catastrophic wave in a popular fjord forces a reckoning with the risks lurking beneath the surface of scenic voyages.
he Wave That Almost Changed Everything
Just before dawn on Aug. 10, 2025, a mountain gave way in southeastern Alaska. Without warning, a massive wall of rock collapsed nearly a kilometer downward, slamming into the South Sawyer Glacier and sending a catastrophic wave surging through Tracy Arm fjord. The tsunami crested at 481 meters — taller than the Eiffel Tower, which stands at 330 meters — making it the second-tallest wave ever recorded in human history.
No one died. But the margin was razor-thin.
A new study published Wednesday in the journal Science — led by Dan Shugar, a geomorphologist at the University of Calgary — provides the most detailed account yet of what happened that morning and, more urgently, what it means for the future of Arctic tourism.
A Near-Miss of Staggering Proportions
At the time the tsunami struck, the fjord was quiet. The early hour meant vessels hadn’t yet entered the narrow, 48-kilometer waterway. But the timing was a matter of fortune, not design.
Within hours of the event, a sightseeing boat from Juneau and a National Geographic expedition vessel — each capable of carrying more than 100 passengers — were due to enter the fjord. The day before, two cruise ships carrying thousands of visitors had already sailed through the area. Another was scheduled to arrive the following day.
The landslide also generated long-period seismic waves equivalent to a magnitude-5.4 earthquake, and triggered a 36-hour seiche — a standing wave that oscillates within a closed body of water — extending the hazard well beyond the initial impact.
Eyewitness accounts revealed the wave’s staggering reach. Kayakers camped on Harbor Island, roughly 55 kilometers away, reported water surging past their tent and sweeping gear into the sea. A passenger aboard a motor vessel in No Name Bay, about 50 kilometers from the landslide site, described seeing waves between one and two and a half meters rise along the shoreline.
Glaciers, Climate, and the Tsunami Connection
The researchers were unambiguous about what made this disaster possible: climate change.
As temperatures rise, Alaska’s tidewater glaciers have been retreating at accelerating rates. In the case of Tracy Arm, the study found that without the rapid glacial retreat, the landslide would likely not have produced such an immense wave — and might not have occurred at all. The exposed rock left behind as glaciers pull back creates unstable slopes prone to catastrophic failure.
The Tracy Arm event falls into a pattern that has been intensifying across the Arctic. A landslide in Kenai Fjords National Park in 2024 generated a wave between 18 and 55 meters. A similar event in Taan Fjord in 2015 produced a 193-meter tsunami. The world’s tallest ever recorded wave struck Lituya Bay, Alaska, in 1958, reaching 530 meters.
The Tracy Arm wave came within 49 meters of matching that record.
Tsunami Risk Grows as Cruise Traffic Booms
The collision of these two trends — rising tsunami risk and surging tourism — is what makes the findings so urgent.
Annual cruise passenger numbers in Alaska have climbed from roughly one million in 2016 to 1.6 million in 2025. Fjords with retreating glaciers, once remote, have become marquee destinations precisely because of their dramatic, ice-carved scenery. Approximately three cruise ships now pass through Tracy Arm daily.
The study’s authors warn that this near-miss cannot be treated as an isolated anomaly. Landslide-generated tsunamis, they note, can produce far more extreme runups than those triggered by earthquakes — particularly in the confined geography of fjords — because the direct displacement of the water column amplifies their force.
Alaska’s Wake-Up Call
Researchers are calling for a sweeping overhaul of how coastal risk is monitored and managed in high-latitude tourism zones. Their recommendations include systematic surveillance of geologically unstable slopes, more accurate tsunami modeling that accounts for landslide dynamics, and stronger protections for communities, tourists and critical infrastructure along vulnerable coastlines.
The morning of Aug. 10 offered a sobering preview of what a worst-case scenario might look like — and a narrow window to act before the next wave comes.
Source: The Guardian