While cruising through Alaskan waters, a group of boaters caught a glimpse of a massive creature in the water.
Immediately, it was clear the animal was a whale, according to a Sept. 11 Facebook post from Alaska Sea Adventures.
“We had an absolutely magical whale sighting over the weekend,” the tour agency wrote in its post. “We could tell instantly when this whale surfaced that [it] wasn’t a humpback, which is the species we see most often.”
It was actually a fin whale, which is an “incredibly rare” sighting in the inside passage of southeast Alaska, the group said. The creature was feeding on krill.
A video shows the huge creature gliding through the water close to the surface.
“We found a unicorn this weekend!” James Begeman, who filmed the encounter, wrote in a Facebook post.
Fin whales are the second-largest whale species, second to blue whales, according to the National Oceanic and Atmospheric Administration. They are known to live along the West Coast, in the Pacific Northwest, Hawaii and in Alaska.
Alaska Sea Adventures said its boat spotted the whale near Warm Springs Bay, which is in southeast Alaska.
Facebook users commented on the video of the encounter, sharing their excitement and awe.
“Incredible footage!” one person commented.
“What a beautiful animal,” another comment said.
“Woowww that is aaaamazing!” a third commenter wrote.