Cephalopods are a class of marine mollusks that includes octopuses, nautilus, cuttlefish and squid—all of which are among the most intelligent and interesting-looking creatures on the planet.

While squid and octopuses are fairly common to encounter on dives, cuttlefish can be more elusive and nautilus are a true rarity to see underwater. Here are some of the best dives for your chance to catch a glimpse.

Squid

Whether it’s coming face-to-face with a giant Humboldt or watching a tiny pygmy squid propel gracefully across a reef, an encounter with one of these 10-limbed cephalopods can make any dive memorable.

One of the most exciting ways to encounter squid is during a blackwater night dive off Kona, Hawaii, when their iridescent bodies pop against a stark black background.

Related Reading: What It's Like to Be an Octopus Researcher

“It’s actually one of the biggest organisms you see on a blackwater dive,” says Casey Nadeau, an instructor and blackwater dive guide at Jack’s Diving Locker, located in Kailua-Kona, Hawaii. “Usually, the organisms people see are about pinkie-fingernail size, but the diamondback squid are bigger than your fist.”

Octopus

There are about 300 species of octopus found across the world’s oceans among rock formations, coral reefs and the deep sea. Their abundance makes these eight-armed creatures a common encounter on nearly any oceanic dive, but Browning Pass Wall off of Vancouver Island, British Columbia, is a sure site to encounter one particular species: the giant Pacific octopus.

“It’s quite amazing to encounter one, especially if they’re free-swimming,” says Makenna Larocque, an instructor at Vancouver Diving Locker. “They can be quite playful.”

Normally, she says, they hide between rocks in what are called octopus dens.

“You can always spot one because there a bunch of shells outside the den,” Larocque says. “After they eat, they spit the shells out there.”

Cuttlefish

Like octopuses, cuttlefish can be found in nearly all marine habitats, from cold, deep waters to tropical shallows. But they aren’t seen in the Americas. If you want a guaranteed cuttlefish encounter, you’ll need to head to the Land Down Under.

Every year between May and August, thousands of Giant Australian Cuttlefish aggregate at Point Lowly off the coast of Whyalla, Australia.

“Watching the cuttlefish interacting with each other, creating an amazing spectacle of cunning games, predation, underwater light shows and colorful kaleidoscopic displays is truly spectacular,” says Teresa Coles, visitor operations coordinator at the Whyalla Visitor Centre and Maritime Museum.

Nautilus

These living fossils spend most of their time in deep water but occasionally migrate up the reef face at night to feed. Nautilus’ stealthy hunting habits mean they are seldom seen on regular dives. However, they’re known to make a rare appearance at a site called Short Drop-Off in Palau.

According to the Sam’s Tours Palau website, Short Drop-Off is one of the only sites where “lucky divers” might see the chambered nautilus.

Related Reading: Mastering the Art of Cephalopod Photography

If you aren't fortunate enough to spy the elusive creatures, you can always visit them topside.

The Palau Aquarium (which is temporarily closed for renovations after a COVID-19 closure) houses two nautilus. "Once we open back for visitors we will have nautilus on display," giving divers the chance to see the creatures up close, says Ilebrang U. Olkeriil, director of the Aquarium Department at the Palau International Coral Reef Center.