One of the enigmas of the sea, the giant oarfish is the world’s longest bony fish. It can reach a length of 56 feet and weigh as much as 600 pounds.

It is also rarely seen because oarfish primarily live at depths estimated to be about 3,300 feet.

However, two of the silvery fish, sometimes known as ribbonfish because of their slender shape and undulating method of swimming, recently made an appearance in the beach shallows off Baja, Calif.

Luckily, staff from Chicago’s Shedd Aquarium were on the remote beach on an ecotourism field trip and captured the encounter on a GoPro camera.

Not much is known about the oarfish’s conservation status because it is so difficult to study. The fish are occasionally pulled up as bycatch in fishing nets. They are thought to occupy a broad range of ocean environments and to feed on krill, small crustaceans and squid.

“It was one of the most stunningly beautiful fish I’ve ever seen,” Tim Binder, vice president of collection and planning for the Shedd Aquarium, who recorded much of the video, told National Geographic. “They had an undulating way of swimming; it was very graceful.”