World's Longest And Most Dangerous Swims

There are the wildly adventurous, but then there are the dedicated few who take on the most dangerous swims in the world. Not only are these brave swimmers who traverse these wild waters subject to sudden changes in weather, but they're also battling unpredictable elements of nature. One never knows when a dangerous animal will approach.

Some of the most dangerous swims have only been completed a few times in history — or not at all. While few have conquered them, that doesn't mean there won't be those brave souls in the future who will make their mark on the world. Remember that the folks who take on formidable challenges like the Amazon River don't do so entirely on their own. They have teams ensuring their safety. A solo swim only means they've done it without a relay, not that they weren't under much supervision. Do not attempt these swims yourself without doing significant research and preparation.

As the name implies, Oceans Seven is not a single swim but a collection of seven different swims. Constituting some of the most dangerous swims in the world, only 27 people have ever completed the challenge in its entirety. The swims include the English Channel, the Catalina Channel, the Strait of Gibraltar, the North Channel, the Molokai Channel, the Tsugaru Channel, and the Cook Strait. Some of the swims are listed here individually as some of the most dangerous swims on Earth.

Altogether, the seven swims total nearly 140 miles of open water. The Strait of Gibraltar is the shortest among them at 10 miles, and the longest is the Molokai Channel at 28 miles. Between the training, travel, and supervision necessary to cross the Oceans Seven off one's bucket list, it'll cost someone as much as $20,000 to complete. Since hundreds of swimmers have failed to finish the challenge, it's a lot of money to put towards a tough goal.

At over 3,200 miles long, swimming the entire Amazon River is a feat. Not only is it dangerous because of its length, but it is also considered the world's most dangerous river due to its unseen perils. Only one person has been known to swim the whole river. In April 2007, Slovenian swimmer Martin Strel became the first (and so far only) person to swim the entire Amazon River. It took him 66 days with a crew of 20 support staff to complete the feat.

Other than the dangerous wildlife that inhabits the Amazon, like the piranha or candirú fish, Strel also had to watch out for myriad other dangers. That included pirates, malaria and Dengue Fever, and floating debris that could be carrying non-water predators like deadly snakes. Somehow, Strel managed to avoid all this and more to complete the swim. Regarding the dangers, he told CNN, "There is no hospital. There are no roads. It's only water and lots of trees, more than a hundred meters high." This is a terrific example of why swims as dangerous as these need (or, in some cases, require) helper boats to follow along.

Did you know that you can technically swim from Africa to Europe? Well, from Morocco to Spain. To be fair, it's only 10 miles. Yet those 10 miles are in some of Earth's most dangerous open oceans, earning the Strait of Gibraltar its spot as one of the swims of the Oceans Seven challenge. The strait is known for its strong winds, varied depths ranging from 980 feet to over 2,950 feet, and its multitude of shipping vessels and orca whales.

Because it's more doable than other dangerous swims around the world, the strait has become more popular than ever. Due to this popularity, there are waiting lists for swimmers that can be more than two years for a one-week swim period between April and November. Swimmers must be able to cover at least 3 kilometers or 1.86 miles per hour even to consider conquering the strait. It is also crucial for potential participants to have plenty of experience with open-water swimming.

Like the Amazon River swim, the Cuba to Florida path of 110 miles has only been accomplished once without using a shark cage. This perilous journey, which took nearly 53 hours of nonstop swimming, has only been completed by Diana Nyad. Besides the nausea and elemental exposure, Nyad also had to deal with water full of stinging jellyfish -–which almost killed her on a previous attempt to complete the swim.

Part of Nyad's journey included returning a green sea turtle named Rocky to the Atlantic Ocean with Florida Keys' Turtle Hospital. Returning Rocky was a special moment for Nyad, who even told Associated Press that she wished the turtle could've joined her on the swim. ​​"The thing I like about them is that they eat jellyfish," Nyad said. "I wish we could have trained Rocky to swim right next to me and eat all the jellyfish that we came upon going across." Nyad's accomplishment so riveted the public that Netflix turned it into a biopic, "Nyad," starring Annette Bening and Jodie Foster.

When Penny Palfrey swam the 67.26-mile length between Grand Cayman Island and Little Cayman in 2011, she broke a world record for the longest unassisted open ocean trek. Wind, choppy water conditions, and sharks are just some of the hazards you'll encounter trying to conquer this challenge, which took Palfrey over 40 hours of nonstop swimming.

Palfrey completed the treacherous swim with an escort boat full of crew and medical staff and a smaller boat and kayaks with navigators stopping to guide, feed, and hydrate her. Besides sharks and water conditions, Palfrey was also up against other unpredictable elements like sun exposure. After the swim, she had to be treated for skin damage, inflammation, internal swelling, and fatigue. She spent two days in the hospital recovering.

"I'm feeling better every single day," she told ESPN, "The first few days I was limited with my talking and I'm pretty hungry because I couldn't eat because of my swollen mouth and tongue. My legs have gone from tree trunks back to legs today, the bruising is disappearing." So, while this swim is possible, it's clearly an extreme task.

It is possible to swim the length of the Atlantic Ocean. Although the more than 3,700 miles is beyond intimidating, a few people in history have done it. Benoît Lecomte was the first to achieve the feat, swimming the distance between Cape Cod, Massachusetts, and Quiberon, France. It took him 73 days to make the historical swim, and he slept on one of the boats that accompanied him.

Lecomte pulled off the feat by swimming six hours a day inside a Shark POD. The POD, which stands for protective ocean device, creates an electronic field that keeps predators at bay. This protects the swimmer without needing more traditional protective equipment like a shark cage. Lecomte's journey even served incredible scientific purposes since he spent such a long period in the water spanning a wide array of areas. Scientists sent along imaging equipment to collect data and hydroacoustic devices to collect marine mammal sounds.

Just short of 140 miles, the length of the Adriatic Sea has been conquered a few times. One such swimmer was Veliko Rogošić, who broke the world record for the longest open ocean swim without flippers when he swam the length of the Adriatic. It took him over 50 hours to complete the swim from Grado to Riccione in Italy.

The Adriatic has over 1,300 islands located within it, though it spans several countries too. Coasts along the sea can be found in places like Montenegro, Bosnia-Herzegovina, Italy, Slovenia, Albania, and Croatia. In total, three basin regions in the sea range in depth up to 4,045 feet. Water in the Adriatic Sea tends to be less salty than water in other large water bodies because of the sea's connection to the freshwater flowing into the Mediterranean Sea. The water here is also a bit warmer than in some of the other dangerous bodies of water we've mentioned, getting down to just about 55 degrees Fahrenheit in the winter.

There is a 236-mile open ocean divide between Cyprus and Israel. Unlike the other swims so far, this one has a record for the longest open ocean swim relay attached to it after a team of six swimmers conquered it in 2014. The Cyprus Israel Swim team of six each did 21 legs of the swim over the course of five days and three hours.

Before this team broke the longest open ocean swim relay record, the Night Train Swimmers out of California set the record. That previous record was 228 miles along the coast of California. The Israeli team conquered the swim after having to call it quits on the route the year before. In 2013, after more than 60 hours of swimming, the team had to stop because of bad water conditions. Some of the waves the swimmers had to endure were between 4.9 and 6.5 feet high at the time.

At a whopping 5,500 miles, the swim between Tokyo and San Francisco has never been completed. Benoît Lecomte, who swam the Atlantic and set a record in 1998, attempted the swim and almost made it after several months but did not complete it. The team projected the journey would take six to eight months of daily swims. Lecomte spent six years preparing for the swim, using the journey to once again work with scientists to gather data along the way.

Lecomte and his team had to call it quits after over 155 days on the open ocean. The water had damaged the follow vessel beyond repair, and they could not safely continue. "I did not have any control over the weather that damaged our boat beyond repair and forced us to stop the swim," he said in his online log via Daily Breeze. The journey was recorded as part of the documentary "The Swim" to commemorate the accomplishment, even if it wasn't met to completion.

Another big river entry in the most dangerous and longest swims on Earth is the mighty and muddy Mississippi River. Few have managed to swim the entire 2,350-mile length of the river that cuts the United States in two. The first person known to swim the whole river was Fred Newton in 1930. He thought it would take him 90 days, but it wound up taking six months.

Early into the swim, Newton ran into manure and animal parts from the St. Paul stockyards. Beyond the gross inconveniences, the upper part of the river also has whirlpools that he had to endure, his brother in a nearby boat documenting the journey. Now, the Mississippi looks much different than when Newton originally swam its lengths, though it's no less challenging to swim. It's also not much less polluted with so much runoff and metal that it leads to a 5,000-mile dead zone in the Gulf of Mexico.

While Newton's trek was record-breaking, others have also completed the journey. Martin Strel and Chris Ring have both also completed the river journey. The river's length, which glides along ten different states, is just one mile shorter than the Missouri River, the longest in the United States.

Martin Strel is the only man who managed to swim the length of the Amazon River and the only one who has completed the entire length of the Yangtze River. The Yangtze is the longest river in China, at over 2,000 miles. Strel had to swim ten hours a day for 51 days to complete the journey. While Strel is known worldwide for breaking open water swim world records, the Yangtze almost ended that career.

Strel told Outside that doctors had to give him daily blood transfusions during the final ten days of his Yangtze swim because the water was so dirty. "The Yangtze almost killed me," he said. "Too much dangers and chemicals. Almost destroyed liver. It was black by end of swim. I swim next to dead bodies human bodies every day. Men facedown, women [face] up. Many dead bodies." This should be no surprise as the Yangtze is one of the world's most polluted rivers. Swimming it was a means for Strel to advocate for clean water and cleaning up polluted waterways across the globe.

Spanning ten European countries, the Danube River's 1,800+ mile length is tempting for marathon swimmers. With that whopping length, the Danube is the second longest river in Europe, second only to the Volga. Once again, this body of water was conquered by famed swimmer Martin Strel, though several other folks have also managed to swim the length as well. Completing the Danube took Strel 58 days of daily swims.

Iancu Avram took on the Danube in an 89-day swim from Donaueschingen, Germany, to Sulina, Romania in 2016. He completed the journey over ten countries without fins or a wetsuit. Along the way, Avram endured whirlpools, eddies, and dams in the river, as well as troublesome weather that made the endeavor more difficult. Sadly, like many of the other rivers Strel has encountered in his career, the Danube is also heavily polluted. It is polluted with millions of gallons of wastewater, heavy metals, and other runoff pollutants.