Alaska’s Megatsunami: How a 500-Foot Wave Nearly Wiped Out a Cruise Ship Hotspot—and What It Means for the Future
May 7, 2026
In the predawn hours of August 10, 2025, a mountain in Alaska’s Tracy Arm Fjord collapsed with the force of 24 Great Pyramids of Giza crashing into the sea. The resulting megatsunami—500 feet tall—was the second-largest ever recorded, yet somehow, no one died. Cruise ships in the fjord that morning survived by mere minutes. Now, scientists warn this wasn’t a fluke. It could happen again—and the next time, the timing might not be as kind.
The Day the Mountain Fell
At 3:47 AM local time, the unthinkable occurred: a section of the fjord’s steep cliffs—estimated at 64 million cubic meters of rock and debris—detached and plunged into the icy waters below. The impact displaced enough water to generate a wave that surged 500 feet (150 meters) up the opposite shore, according to the Alaska Earthquake Center. For comparison, that’s taller than the Eiffel Tower.
The wave’s energy created a seiche—a standing wave that sloshed back and forth in the fjord like water in a bathtub—for hours, generating seismic vibrations detectable globally for up to 36 hours. Cruise ships, including those operated by major lines like Holland America and Princess Cruises, were in the fjord at the time. Passengers later reported feeling the ground shake before the wave passed beneath them, unaware of the catastrophe that had just unfolded.
“We know that there were people that were extremely nearly in the wrong place. I’m quite terrified that we’re not going to be so lucky in the future.”
Why Did No One Die?
The survival of hundreds of passengers and crew aboard cruise ships that morning was a matter of timing. The landslide occurred in the early hours, when most vessels were anchored or moving slowly. Had it happened during peak tourist hours—when ships are navigating closer to the cliffs for scenic views—the death toll could have been catastrophic.
Tracy Arm is a bucket-list destination for Alaskan cruises, known for its sheer cliffs, glaciers, and wildlife. The fjord is regularly traveled by ships carrying thousands of passengers annually, making it one of the most trafficked areas in Southeast Alaska. The 2025 event was a stark reminder of nature’s unpredictability in a region where tourism and geology collide.
Alaska’s Megatsunami Legacy: Tracy Arm vs. Lituya Bay
The 2025 Tracy Arm megatsunami wasn’t an isolated event. Alaska has a long history of producing the world’s most extreme waves—all triggered by landslides.
| Event | Location | Date | Wave Height | Cause | Casualties | Notable Fact |
|---|---|---|---|---|---|---|
| Lituya Bay Tsunami | Gulf of Alaska | July 9, 1958 | 1,720 feet (524 meters) | Earthquake-triggered landslide (30.6 million cubic meters of rock) | 5 deaths | Still holds the record as the highest tsunami ever recorded. |
| Tracy Arm Megatsunami | Southeast Alaska | August 10, 2025 | 500 feet (150 meters) | Massive landslide (64 million cubic meters of debris) | 0 deaths | Second-largest recorded; occurred during peak cruise season. |
Source: United Nations Office for Disaster Risk Reduction, Alaska Earthquake Center
What Caused the Landslide—and Could It Happen Again?
Researchers from the Alaska Earthquake Center and the U.S. Geological Survey (USGS) have identified several key factors that contributed to the 2025 disaster:
- Glacial Retreat: The rapid melting of Sawyer Glacier—accelerated by climate change—has destabilized the surrounding cliffs. As glaciers recede, they remove support from the rock above, making landslides more likely.
- Permafrost Thaw: Rising temperatures in Alaska are thawing permafrost, which can weaken the structural integrity of mountainsides. The USGS notes that permafrost loss has increased landslide risks by up to 30% in some regions.
- Seismic Activity: While the 2025 landslide wasn’t directly triggered by an earthquake, the region is seismically active. Even minor tremors can dislodge unstable rock.
The Alaska Earthquake Center classifies the Tracy Arm landslide as the largest in at least a decade, raising concerns that similar events could occur in other Alaskan fjords. Dr. Higman warns that the scars left by the 2025 slide—visible even from satellite imagery—are a warning sign.
“We all go to these stunning places given that we want to experience the beauty, and we want to be humbled by nature. That scar that is there by the glacier is always going to be a reminder that this has happened there, and it can happen anywhere else.”
The Human Factor: How Cruise Lines Are Responding
In the wake of the 2025 disaster, major cruise operators have begun revisiting their safety protocols in Alaska. While no official changes have been publicly announced, industry insiders report:
- Expanded Monitoring: Ships now carry enhanced seismic sensors and real-time communication with the National Weather Service’s Alaska Avalanche Information Center.
- Route Adjustments: Some itineraries have temporarily altered paths to avoid high-risk areas near Tracy Arm and Lituya Bay.
- Passenger Briefings: Crew members are now required to conduct mandatory safety drills for Alaskan fjord crossings, including megatsunami evacuation procedures.
However, experts argue that more must be done. The Alaska Earthquake Center has called for:
- A real-time landslide detection system for high-risk fjords.
- Expanded bathymetric mapping (underwater terrain data) to identify submerged hazards.
- Stronger international tsunami warning protocols for remote cruise routes.
FAQ: Your Questions About Alaska’s Megatsunami
1. Could a megatsunami like this happen elsewhere in the world?
Yes. While Alaska is the most active region for megatsunamis due to its glaciers and seismic activity, similar events have occurred in Norway, Greenland, and even Indonesia (e.g., the 2018 Palu tsunami). Any fjord or coastal area with unstable cliffs and water bodies is at risk.
2. Why weren’t there more deaths in Tracy Arm?
The timing was critical—the landslide occurred at 3:47 AM, when most ships were anchored or moving slowly. The fjord’s narrow shape contained the wave’s energy, preventing it from spreading far. Had it happened during peak tourist hours, the outcome could have been far worse.
3. Is climate change making these events more likely?
Absolutely. The USGS and Alaska Earthquake Center both link glacial retreat and permafrost thaw to increased landslide risks. Warmer temperatures weaken mountain stability, making catastrophic collapses more probable.
4. Are cruise lines doing enough to protect passengers?
While protocols have improved, many experts believe more can be done. The lack of a dedicated megatsunami warning system for Alaska’s fjords remains a gap. The Alaska Earthquake Center has urged the National Tsunami Warning Center to expand coverage to include cruise ship routes.
A Warning for the Future
The Tracy Arm megatsunami was a wake-up call—not just for Alaska, but for the entire cruise industry. While the 2025 event was a near-miss, scientists warn that the next one might not be so lucky.
As climate change accelerates glacial melt and permafrost degradation, the frequency of such events could rise. The question is no longer if another megatsunami will strike, but when—and where.
For now, Alaska’s fjords remain some of the most breathtaking destinations on Earth. But as Dr. Higman puts it: “Nature doesn’t care about our schedules. We’re the ones who necessitate to pay attention.”