Imagine swimming continuously for nine days in freezing waters — sounds impossible, right? Yet, a female polar bear did just that, covering a staggering 687 kilometres across the icy Beaufort Sea north of Alaska.

The marathon swim was first reported by the media more than a decade ago, in early 2011. Recently, glimpses of this incredible endurance feat resurfaced on social media, reigniting discussions about climate change and wildlife survival.

The video was posted on X. The polar bear was tracked using a radio transmitter, which was installed by a team of scientists working for the US Geological Survey in late 2008, when she was first collared. Her remarkable nine-day swim was initially reported in 2011.

The female bear’s journey, however, did not end with the 687-km swim, as she went on to cover an additional 1,800 km in search of a new ice floe. The gruelling expedition ultimately caused her to lose nearly 20% of her body weight.

The resurfaced video has attracted significant attention from users, many of whom marvelled at how the polar bear managed to survive without food for nine consecutive days.

One user asked, “Wouldn’t it feel tired."

Expressing their disbelief, another user said, “Polar bears are incredible animals! I can’t believe she didn’t take a single break!"

One of the comments read, “Polar bears thrive in cold environments, and their fat composition plays a crucial role in this. They can consume up to 20% of their body weight in a single meal, which is equivalent to eating over 200 blocks of butter for an adult male. This impressive ability to feast underscores the importance of fat in their diet, particularly in the form of seal blubber."

The video, captured from an aerial perspective, shows the polar bear swimming past highly fragmented ice floes along the fragile coastline.

In response, one user shared another clip, purportedly showing a mother polar bear breaking the frozen surface to help her cub breathe at regular intervals during their underwater journey.

While the footage has captivated social media users, it highlights a troubling reality of climate change. Experts warn that the early melting of Arctic ice is forcing polar bears to undertake increasingly long swims, far beyond their natural endurance, in search of suitable habitats.