Have you ever wondered how humpback whales sleep?

A group of underwater photographers known as Panga MX says it captured rare footage of the majestic marine mammal snoozing earlier this year. “We encountered a sleeping humpback whale and managed to get an in-water encounter with her,” the group wrote on YouTube on Oct. 10. “This is a short clip of a 20 minute encounter showing her come up to breath and check us out.”

What an astonishing sight.

Unlike human beings, humpback whales are conscious breathers, which means they have to remember to breathe, even while sleeping. According to Animal Planet, it’s believed that humpback whales only shut off half of their brain at a time while asleep, so as to be alert enough to breathe.

Some humpback whales have been documented sleeping upside down (like the one in Panga MX’s video), while others have been spotted sleeping horizontally, floating either near the surface (a state known as “logging”) or farther underwater.

In general, dolphins and whales have two basic ways of sleeping, according to Scientific American. They either “rest quietly in the water, vertically or horizontally, or sleep while swimming slowly next to another animal.”

Sperm whales, for instance, have been photographed floating vertically with their tails down.