A GPS-tracked wolf did something stunning in Switzerland; it swam into Lake Lucerne and left experts searching for answers

A male wolf criss-crossing Switzerland did something researchers say had not previously been recorded. Rather than taking the longer, presumably easier route around Lake Lucerne, the animal dove into the cold water and swam roughly 1.5 kilometres across the lake.

The wolf, designated M637, was being tracked by a GPS collar as part of a wildlife monitoring project run by KORA, the Swiss carnivore research foundation.

Tracking data showed the wolf entering the lake and crossing it on February 13, 2026, in winter conditions, with lake temperatures reported to be around 5 degrees Celsius. KORA said this is the first recorded instance of a wolf crossing Lake Lucerne, providing researchers with a rare glimpse into how the animals navigate an increasingly fragmented landscape.


A journey no one expected

When the biologists first reviewed the tracking data, they reportedly tried to come up with alternative explanations. KORA biologist Flurin Kunz was quoted by Swiss public broadcaster SRF as having initially attempted to ascertain if the wolf had travelled around the lake via land. But KORA's GPS timestamps for M637 did not support that theory. One data point was located smack in the middle of the lake, while subsequent points put the animal on opposing shores within a short time span.

The evidence indicated that M637 swam across the lake. Swissinfo reported that the wolf appeared on one side of the lake and then on the other within approximately 90 minutes, making a land detour highly unlikely.

Why would a wolf choose to swim?

It might seem like a baffling decision for a wolf to enter a frigid body of water.

But wildlife experts suggest it was likely the most efficient way forward for the wolf. M637 is believed to be between 3 and 4 years old and may have been undertaking a dispersal journey in search of territory and potential mates.

Those journeys can be long, stretching over hundreds of kilometres.

Rather than navigating roads, villages, and developed shorelines, M637 may have simply seen the lake as a more direct shortcut. KORA's data also show M637 has already traversed several Swiss cantons, crossed transport corridors, and moved through various landscapes in his quest to find territory. From late January to early March, for example, M637 travelled approximately 739 kilometres.

GPS technology revealed a hidden behaviour

Without the tracking collar, it’s unlikely anyone would ever have known that M637 had crossed the lake.

According to KORA, the wolf was outfitted with the GPS transmitter in October 2025 as part of its "Wolves and Cattle" research program, which gathers movement data to study how wolves interact with landscapes and livestock areas.

The lake crossing demonstrates the value of animal tracking. Without the collars, large carnivores may move through inhabited landscapes and engage in unseen behaviours, the researchers noted. KORA called the incident an example of the challenges that dispersing wolves face as they travel across Europe.

Wolves are good swimmers, but these sightings are rare

While not aquatic animals by any means, scientists know wolves are capable of swimming. According to a National Geographic report on the “sea wolves” of Canada’s Pacific coast, wolves swim between islands and cover significant distances in open water. Some wolves have been recorded swimming for several kilometres as they seek out food or establish territories.

The unique aspect of M637’s journey is not so much the swim itself, but where it happened.

The wolf made his passage through Lake Lucerne, a lake in central Switzerland surrounded by settlements, transportation corridors, and recreational areas. M637 appeared to simply use it as a quick thoroughfare.

A sign of wolves returning to Switzerland

The incident occurred as wolves continue to expand their presence in Switzerland, a century after the species was decimated by hunting and persecution.

KORA's monitoring data indicate dozens of wolf packs were confirmed in Switzerland during the 2025-2026 monitoring year.

For KORA, M637's lake crossing is more than just a curious anecdote about an animal. It's an example of how the large predators, in their return to European landscapes transformed by humans, continue to adapt in surprising ways.

As for M637, he continued his wanderings across Switzerland and into neighbouring France. Whether he will one day settle down and start his own pack is unknown. But a wild wolf is not likely to be soon forgotten after taking an impromptu winter swim across a Swiss lake.