Shipwrecks from our planet’s most notorious wars delight explorers off Europe, while in-your-face encounters with one of nature’s most skilled predators, the orca, thrill travelers in Norway. And who can forget the Atlantic outposts in the Canary Islands and Azores, where unforgettable diving awaits anyone who plunges into the deep in hopes of getting their adrenaline fix.

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A wonderful immersion with so much life, Playa Chica is one of the most frequented diving sites in the Canary Islands. With easy access directly from the beach, this site has something for every type of diver, from the vertical walls hiding marine life all the way down to the deep white sand bed — there’s even a small wreck. Once you start the dive, you’ll find all sorts of friendly ocean life, from groupers and frogfish to beautiful orange corals and enormous barracuda, and Playa Chica is a perfect candidate for night diving when conditions are right. — Francis Pérez

Teeming with marine life, the island of Santa Maria is one of the most interesting and diverse in the world. Diving at this location means stunning visibility in summer season and devil rays, groupers, snappers, huge stingrays, moray eels, invertebrates, crustaceans and schools of fishes. When you add the chance of finding sea turtles, varied species of dolphin, whale sharks, the elusive oceanic sunfish or the giant oceanic manta ray, this adventure becomes a visual feast and a truly unforgettable experience. Baixa do Ambrosio, located only a couple of miles from the coast of Santa Maria, belongs to a marine-reserve area and is a must-dive location for encounters with devil rays and, for the more experienced divers, large schools of barracuda and amberjacks. Groups of devil rays 20 to 30 strong are quite common; they swim in circular directions, coming close to underwater photographers, and are not afraid of bubbles or the lights of the underwater strobes. — Sabrina Belloni

SS Kronprinz Wilhelm

Scapa Flow, Scotland

Divers from around the world flock to the Orkney Islands to dive the remains of the German World War I High Seas Fleet, and the highlight of this rusty mecca is the 480-foot Kronprinz Wilhelm. This battleship will blow you away with its sheer scale (it sits on the bottom in 125 feet but rises to within 40 feet of the surface), and if you drop to the seabed and head under the hull, you’ll find the barrels and turrets of the main 12-inch armament in all their imposing glory. — Mark Evans

The waters surrounding Vis Island in the Adriatic Sea hold memories of fierce battles. The sandy bottom is dotted with wrecks dating back to both world wars and beyond. The diving here is excellent, meeting the expectations of both recreational and technical divers who want to explore. The wreck of the B-24 Liberator bomber Tulsamerican lies at 130 feet, not far from the wreck of a B-17G Flying Fortress, which is at 230 feet. Both are in very good condition and bursting with life — clouds of anthias whirl among the structures, which are covered by encrusting and yellow sponges. Heavily damaged during their final battles, both airplanes were attempting an emergency landing on the small landing strip built on the island of Vis. It was the last chance for many U.S. bomber crews who couldn’t make it back to their southern Italian bases, but they weren’t all successful. — Sabrina Belloni

Facing the Arctic, Andenes Fjord is the theater for a spectacular event orchestrated by fantasy animals, reserved for those who are ready to face the cold. In January, herrings migrate into the fjords, attracting many marine predators, such as humpback whales, fin whales and especially orcas. These killer whales hunt this fish by creating baitballs. Immersing yourself in the middle of the fjord to witness this behavior allows you to approach the orcas very closely, a sensational experience accentuated by a special atmosphere with the snowy landscapes that line the fjords. You will need to equip yourself to enjoy the moment — a drysuit for diving and warm clothes to go outside to watch the dance of aurora borealis at nightfall. — Greg Lecoeur

Orda Cave

Russia

There is no daylight zone in the Orda Cave, and the temperature is only 42 degrees Fahrenheit year-round. But the result is mystical: giant white grottoes and labyrinths of narrow passages decorate this otherworldly site. The length of its flooded portion reaches almost 17,000 feet, and the cave is shallow, with a typical average depth at about 26 feet, so you can stay and explore with extended bottom times. The inner space of the cave is decorated with sculptures of fragile gypsum. The most famous of them are White Dragon and the silhouette of a woman on the wall, the Lady of Orda Cave. — Bogdana Vashchenko

Unusually, the wow moment comes right at the very beginning. It is the process of dipping your mask beneath the surface of Silfra Crack that blows your mind. Silver Canyon gets its name because the dark waters reflect the white clouds above and show little of what lies beneath. It’s only at the moment of submergence that you pass through the looking glass and everything is revealed. Suddenly the scale of the chasm is apparent, and because you can see so much more than you could from above, you get the feeling that the water is even clearer than air. In fact, the stunning visibility is almost impossible to gauge because, despite the size of this fracture that divides the North American and Eurasian continental plates, you can never see far enough in a straight line to judge it. There is always a turn in the canyon before the viz runs out. “Silfra always gets amazing reactions,” says Finni Finnbjornsson, of Scuba Iceland. “People are always blown away by the spectacle and visibility, however much they have read about it before.” — Alex Mustard

The wreck of the Zenobia is the most famous wreck at Cyprus, but there are two more vessels that can be explored near Limassol, which is located about one hour west of Larnaca. In contrast to Zenobia, these purpose-sunk wrecks are therefore free from any dangers such as cables or ropes. The Lady Thetis is a former fishing boat whose helm offers a great photo subject and several large grouper a beautiful home. The other wreck, the Constandis, is a former excursion boat where the engine room can still be dived, along with the intermediate deck with a large staircase in the middle. On the sun deck there are still several fixed tables and stools. — Tobias Friedrich

Only a few minutes away by boat from Puerto de la Cruz, this visually mesmerizing formation is for experienced divers because it’s an average of 100 feet with a maximum depth of 150 feet. It’s one of the most surprising and beautiful places in the islands. Almost a million years ago, there was a volcanic eruption near the coast and the lava reached the sea, solidifying and creating these spectacular hexagonal columns. It’s possibly one of the biggest columnar jointings in the world. It’s also one of the legendary spots for diving in the north of Tenerife. You may occasionally find ocean currents here, but that’s when you’re able to see the whole of the structure very clearly. Diving here gives you the feeling of being on another planet, or even in an underwater city in ruins. — Francis Pérez

The town of Penzance clings to the very southwest tip of England, overlooked by the castle atop St. Michael’s Mount. The mount is an island at high tide, connected to the mainland by a cobbled causeway that floods as the waters rise. The underwater attraction here is the chance of seeing the world’s second-largest fish — the basking shark. Baskers can grow to a massive 40 feet in length, although most are in the 20- to 30-foot range — still quite impressive. Their dorsal fins are oversize and certainly get your heartbeat going when they are bearing down on you. These sharks show up in the summer and are usually seen feeding at the surface, filtering plankton with their gaping mouths. Calm, sunny weather brings the zooplankton to the surface, in an attempt to avoid predation by mackerel and other fish. However, by massing at the surface, the plankton create a feast for the sharks. The densest plankton is often concentrated close to shore, and the sharks follow suit. Tourists visiting the castle are regularly surprised when they look down into the water and see sharks and, perhaps, some lucky divers. — Alex Mustard

This classic ocean liner — which was converted to an armed merchant cruiser for the Great War — left Loch Swilly in Ireland at the height of World War I to deliver 43 tons of gold to the United States as payment for war supplies. Shortly into the journey, it struck two mines and went down in 130 feet of water, along with 350 of its crew. A century later, this atmospheric wreck is shrouded in clear green water and teems with marine life. From the picturesque bow, which lies on its side, you head aft over a wreck that has been flattened like a pack of cards by sea action, yet is littered with remnants of its past. Soon you will reach a deck gun that points the way to row after row of the giant Scotch boilers, which provided the power needed to propel this enormous 550-foot-long steamship across the Atlantic. As for the gold, multiple salvage operations attempted to recover it, but to this day, 20 bars, worth $10 million, remain unaccounted for! — Steve Jones

The opal mines hidden in eastern Slovakia — near the city of Presov — hosted treasure hunters as far back as the 16th century as they dug deeper into the earth to uncover these precious gemstones. The hard work has been done for those hunting for a precious dive site; today, there are more than 13 miles of tunnels and shafts, about 3 miles of which is flooded to the delight of visiting divers. The characteristics that made opals so desirable throughout history also make this dive special today. Divers can mosey down the corridors of this massive mine, appreciating the kaleidoscopic walls that shimmer with hues of purple, pink, blue, green and orange. Each dive into the mine is like a foray into time travel; the handiwork of miners from long ago is evident. Corridors lead to areas cut out above and below, and into wide-open ballrooms. Stop to appreciate the highlight of the opal mine: the main vertical mining shaft known as Fedo. The iron rails leading upward can be seen from two flooded floors, leaving divers with the feeling that a cart from the past could appear at any moment. The visibility is seemingly endless in the chilly 37-degree water, providing the perfect photo op in one of the world’s truly unique dive settings. — Andy Zunz

When conditions are at their peak — in April, visibility can reach 100 feet underwater — stare down into the blue to see 90 percent of this massive iceberg from the surface. The structures of the giant in southeastern Greenland shimmer blue-greenish in the strong sunlight. The colossus reveals unexpected forms, similar to a reef with canyons, coves and small plateaus, which extend far beyond the structures of the iceberg that can be seen over the water’s surface. In some places, sharp edges like oversize axes rise from the ice, and in others, the ice is traversed by fine cracks that run like veins through it. Almost everywhere is a thin, transparent layer of ice over a solid white core that looks like snow. — Tobias Friedrich

Sitting amid an area known for its wrecks and caves, the P29 is still a favorite for the local divers of Malta and Gozo. This minesweeper, built for the German navy and put into service in 1970, was eventually transferred to Malta as an unarmed patrol boat. The 170-foot ship was purpose-sunk near Cirkewwa Harbor in 2007 and has since become a popular dive. The bow is resting in 120 feet and the upper deck is accessible at 105 feet, but potential current makes this a site best suited for advanced divers. — Gerald Nowak

Portofino Lighthouse

Italy

Famous for the big groupers that can be observed here, the Portofino Lighthouse is a unique scene, especially during early morning or sunset dives. At these times, something extraordinary happens: Groupers and morays come together to hunt octopuses. Divers stay on the bottom at 40 feet and wait. Octopuses try to find a safe place to recover, but morays don’t permit it, standing precisely in front of their den. The groupers begin incursions immediately, and most of the time, some octopuses fall victim to the hunt. Fight to survive — it’s the law of the sea. — Isabella Maffei