America’s coastlines are truly beautiful, but deep in its waters, there is a whole other world to explore. From spooky shipwrecks and underwater museums to mystical caverns and submarine adventures, here we take a look at the most incredible underwater sights in the US that are bound to impress.

Just a few miles off the Sunshine State's coastline, the Florida Keys Shipwreck Trail follows a series of sunken ships scattered along the coral reefs and sandy shallows of Key Largo. The shipwrecks range from historic Spanish vessels to more modern ships that were intentionally sunk. Notable wrecks that divers can explore include the SS City of Washington which sank in 1917 and the oldest wreck, the San Pedro, which formed part of the 1733 Spanish treasure fleet.

Best known for its inflatables on a 50-acre lake in Pennsylvania, there's more to Dutch Springs than its colourful obstacle course. Beneath the surface, the lake has plenty of hidden delights to discover, including a sunken school bus, fire truck and an aircraft at depths of up to 100 feet (30.5m). The quarry lake is spring-fed from an underground aquifer that filters through limestone, providing excellent visibility for diving. Newbies can learn the ropes on one of the scuba diving courses, while more experienced divers can plunge right in. 

Tucked away in the heart of the Midwest, the Bonne Terre Mine is one of the largest man-made caverns in the world. Founded in 1860, the mine was the world’s largest producer of lead ore until it closed in 1962 and was later flooded and transformed into a popular diving site. The mine’s Billion Gallon Lake is illuminated with over 500,000 watts of lighting, dotted with dive trails. With over 100 feet (30.5m) of visibility, there's a lot to see – notable sights include staircases, pillars and the famed elevator shaft. 

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Located three miles (4.8km) off the coast of Miami Beach, the Neptune Memorial Reef is the largest man-made reef ever conceived. The reef is an artistic representation of the Lost City of Atlantis, featuring sunken columns, roadways and lion statues roughly 40 feet (12.2m) below the surface. The mystical reef also serves as the final resting place for ocean-loving souls, and is dotted with headstones containing the ashes of loved ones. Once complete, the Neptune Memorial Reef will transform over 16 acres of the ocean floor.

The first national marine sanctuary of the Great Lakes lies just off Michigan's coastline. The Thunder Bay National Marine Sanctuary is home to more than 100 shipwrecks which range from a few inches to 200 feet (61m) deep. Beautifully well preserved, the historic ships are well marked, making it perfect for beginner divers to explore and discover Michigan's maritime heritage. Visitors can dive, kayak, snorkel or take a tour of "Shipwreck Alley" on a glass-bottomed boat.

Stretching just west of Munising towards Au Sable Point in Michigan, the Alger Underwater Preserve lies on the south shore of Lake Superior. Sheltered by Grand Island, its waters are littered with several remarkably well intact shipwrecks including the Bermuda, Smith Moore and Manhattan alongside an array of underwater interpretive trails. There are plenty of rock formations to discover too, including a portion of the Pictured Rocks National Lakeshore’s sandstone cliffs that have become underwater sea caves and are a sight to behold.

Renowned for being America’s first undersea park, this vibrant reef covers roughly 70 nautical square miles (240 sq km). Created to protect a portion of the only living coral reef in the continental US, the John Pennekamp Coral Reef State Park is teeming with marine life, making it popular with snorkellers and divers. Its most notable underwater sight is the sunken algae-coated statue of Jesus Christ (pictured) with outstretched arms, that looks magical when illuminated by sunlight.

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Atlantis Submarines (part of Atlantic Adventures) has been exploring the undersea wonders of Hawaii since 1988. Using battery-powered environmentally safe submarines in Waikiki, the company takes passengers over 100 feet (30.5m) deep, past famous dive sites like Leahi (Diamond Head) which is frequented by green turtles, sharks, stingrays and eels. In Maui, visitors can discover the Atlantis Undersea Adventure and see some truly spectacular marine life there too.

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Once an impressive warship, Spiegel Grove is one of the largest artificial wrecks purposely sunk off the Florida Keys. Decommissioned in 1989, the ship was sunk in 2002, creating a new reef for divers. Since then, the wreck has become a hot spot for marine life of all kinds, making it a pretty diving spot which plunges to a maximum depth of around 130 feet (39.6m). Marine scientists expect that natural coral may eventually cover the old ship, creating its own reef ecosystem. 

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Less than an hour's drive from Los Angeles’ Long Beach in the shadow of the Catalina Casino on Catalina Island is a hidden world of underwater beauty. At the Casino Point Dive Park, swaying kelp decorates the ocean floor, while black sea bass and orange garibaldi swim through the greenery and clear blue waters resembling a scene from a fairy tale. Two historic shipwrecks also lie in the watery depths for divers to explore.

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Dubbed the Manatee capital of the world, Crystal River in Florida is home to more manatees than anywhere else on the planet. Each winter between 500 and 1,000 manatees are drawn to the river’s waters, as it is one of the warmest water refuges for the marine mammal along the Gulf Coast of Florida. Crystal River is also one of the few places where visitors can have an in-water experience with the manatees in their natural habitat through a guided snorkelling tour.

A hidden gem of Tennessee, Martha’s Quarry is home to one of the biggest underwater sites of industrial wreckage in the US. The 60-foot (18.3m) quarry is littered with cool submerged treasures, including an old airplane, a car and the quarry’s original crusher house. Divers can swim along the conveyor belt, while watching the streams of fish as they swim by. For those new to deep sea diving, Martha’s Quarry offers scuba diving training too.

Nestled along the banks of the Santa Fe River in Florida, this little slice of paradise is one of the most popular freshwater dive sites in the world. Already picturesque above the surface, plunge deep into the watery depths of Ginnie Springs and you’ll come across a string of incredible dive sites. At 15 feet (4.6m) deep, Ginnie Ballroom is the site’s biggest draw, home to the Ginnie Cavern which is studded with unusual rock formations, made even prettier when sunlight streams through.

Just a short boat ride from Kauai’s Poipu Beach is one of Hawaii's most diverse and vibrant dive sites. The caverns are made up of three large lava tubes, providing shelter from ocean swells. Its waters are frequented by marine life such as lobsters, turtles and shrimp as they swim between the nooks and crannies, while dolphins and humpback whales can be seen above the surface, earning the area its nickname 'The Circus'. With its undisturbed coral and calm waters, Sheraton Caverns is perfect for divers of all levels.

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A sparkling jewel of the Florida Keys National Marine Sanctuary, with its beautiful marine life and colourful coral, it's easy to see why Molasses Reef is one of the most visited diving spots in the Upper Keys. The vibrant reef is famous for its clear waters, boulder corals, pretty caves and the plethora of fish that call it home, offering plenty to see for divers and snorkellers. In the heart of the reef, divers will discover a large ship’s winch and historic anchor, reminiscent of a fish tank.

Established as a conservation area in 1970, the Edmonds Underwater Park in Washington has been an important resource for the Edmonds community for over 50 years. Located just north of Seattle, the park encompasses more than 27 acres of tide and bottom lands with trails created especially for divers. It features a series of man-man reef structures alongside sunken vessels in various states of decay, forming a vast artificial habitat for marine life, with ropes making it easier to swim around the park. 

Located near Lower Matecumbe Key, the Eagle is a former cargo ship that has been transformed into an artificial reef. Built in the Netherlands in 1962, the cargo ship was en route to Venezuela when it caught fire in 1985 and was deemed beyond repair. The impressive ship was docked in Miami and then later intentionally sank at Alligator Reef as part of an artificial reef programme. Since then, at 110 feet (33.5m) deep, the Eagle has become a refuge for marine life and is regarded as a prime diving destination.

From ground level, this may look like an ordinary park in Texas but beneath the surface is a wreckage playground. The Athens Scuba Park was developed from an old clay slag pit fed from the water of a nearby spring. The 50-acre property is home to a lake with a depth of up to 30 feet (9.1m) filled with more than 20 sunken wrecks. Highlights include several buses, sailboats, an airplane and a grand piano. 

Set a mile off the coast near Mission Bay, San Diego's Wreck Alley is an artificial reef famous for its sunken ships and unusual structures. The crown jewel of the diving site is the 366-foot (111.5m) HMCS Yukon, a Canadian destroyer which was sunk in 100 feet (30.5km) of water in the Pacific Ocean. With its maze of tunnels and passageways offering plenty to explore, the massive ship has firmly cemented Wreck Alley as one of California's top diving destinations. 

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Just off the coast of the Hawaiian island of Lanai is an underwater wonderland like no other and one of the best diving spots in the state. The Lanai Cathedrals are two beautiful lava caves, filled with caverns, arches and swim-throughs. Light from the surface streams into the caves while schools of fish such as orange menpachi, reef sharks and turtles swim between the rocks, creating a truly enchanting scene for divers.

A haven for scuba divers, Jules' Undersea Lodge is the only underwater hotel in the US. Part of the Key Largo Undersea Park, the Jules' Lagoon is filled with interesting wildlife and artefacts, with plenty to see and do. Guests have to scuba dive to their room, which features a porthole with underwater views of the lagoon. The lodge is stocked with plenty of refreshments and a pizza of your choice will be delivered to your room.

Now discover the world's most jaw-dropping underwater attractions

Another gem from Florida, Weeki Wachee Springs State Park can be found along the state's Nature Coast, north of the cities of Tampa and Clearwater. A proud symbol of the yesteryear of Florida’s tourism, the park is home to the deepest known freshwater cave system in the country. Alongside its deep waters and pretty spring, Weeki Wachee is best known for its legendary mermaids. The mythical mermaids perform underwater feats of delight alongside their version of The Little Mermaid in a submerged auditorium.

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