Adventurous tourists on an expedition to explore Wrangel Island Nature Reserve in the Arctic recently got their money's worth with an encounter of a lifetime. As they approached the island aboard the vessel Akademik Shokalskiy, they witnessed what appeared to be a flock of grazing sheep, reports GrindTV. But upon closer inspection, it became apparent that these were no sheep. They were an immense congregation of something much more ominous: polar bears.

Polar bears are usually solitary animals, but these apex Arctic predators had improbably gathered by the hundreds — an estimated 230 of them.

It was "one of those days I or anybody else with me will never forget," claimed Capt. Rodney Russ, leader of the expedition.

A gathering this large might be unprecedented, truly a remarkable sight. It didn't take long to solve the mystery as to what was going on. The bears were concentrated around a massive whale carcass that had washed ashore. With so many bears in such a small area, it's a wonder that they all seemed capable of tolerating one another, but a whale carcass provides plenty of food to go around.

Pictures of the scene were captured by officials on site. You can view a few of them here:

wrangel polar bears Sheep, or polar bears? (Photo: A. Gruzdev/Wrangel Island Nature Reserve)

polar bears Polar bears on Wrangel Island (Photo: Wrangel Island Nature Reserve)

Wrangel Island hosts the highest density of polar bear dens on the Earth, with as many as 400 mother bears utilizing the island each winter to raise their young. Over the last several years, the population density on the island in the summer has increased to historic numbers due to the disappearing ice packs that once enveloped the island, forcing the bears to remain land-locked.

Sightings like this could become more commonplace if nothing is done to curb global warming, Though thrilling to witness, such large polar bear gatherings are not normal, and they could represent signs of ecological stress. It's an unfortunate wake-up call that even our most remote protected areas are vulnerable to climate change.