We still don’t know

An immortal jellyfish? 10 spooky and unanswered questions about the sea

Some people are scared of the ocean. Can you blame them? Though waters cover 70% of our planet, scientists are still scratching their heads about certain unanswered questions. How long can blue whales actually live? What substance makes some waters glow eerily white at night? And what’s with the self-rejuvenating, immortal jellyfish? These are some of the mysteries we’ll explore in this article!

Found abandoned in 1872 with sails set, cargo intact, and dinner still on the table, the Mary Celeste is the poster child for maritime enigmas. The whole crew vanished without a trace and was never heard of again.

Mutiny? Rogue wave? Alcohol fumes? Giant squid? No theory fully fits. It's a fascinating tale that has been the subject of documentaries, theatre plays, novels, and movies.

For centuries, sailors have reported seeing entire portions of the ocean surface glowing white at night, like a ghostly reflection.

An explanation could be massive blooms of bioluminescent bacteria, but no one knows how they coordinate light across such huge distances or why the phenomenon lasts for hours. Even with satellite detections, it remains one of the ocean’s eeriest light shows.

Tales of a giant squid have been alive for centuries, but it was only in 2004 that humanity was able to photograph this fabled creature. In that year, a Japanese team captured a live one on camera in its natural habitat and finally proved that the creature behind centuries of sea-monster legends was very real.

And yet, we still know shockingly little about its life cycle, breeding habits, or how something that big stays so well hidden.

You’d think the largest creature ever to exist would be the easiest to study. Nope. We still struggle to track migration patterns, understand their communication system, or explain the full recovery timeline after they were nearly hunted to extinction.

Turritopsis dohrnii cheats death by reverting its adult cells back to a juvenile state when stressed. It’s like if a human under pressure suddenly turned back into a toddler.

This regeneration process is wildly complex and not fully understood, and scientists hope that cracking its secret might reveal insights into aging itself.

The stretch between Florida, Bermuda, and Puerto Rico has inspired endless theories. Unexplained disappearances, bizarre compass behavior, and strange weather patterns have contributed to building the legend.

Scientific explanations abound, from methane hydrates to violent storms, but the Triangle’s mythic aura refuses to die.

The Challenger Deep, the trench’s lowest point, plunges almost 7 miles. Only a handful of people have ever explored its bottom, including filmmaker James Cameron in 2012.

What lives down there? What geological processes unfold under such pressure? Every new expedition reveals creatures that look like they belong in fever dreams.

Off the coast of Japan lies a submerged stone structure with terraces, pillars, and sharp geometries that seem carved… Unless they were shaped by strange phenomena of nature.

Some believe it’s the remains of an ancient city, sunken after an earthquake; others argue it’s purely geological. Today, it’s a riddle lying quietly under turquoise waters.

In 1918, a massive US Navy collier vanished without a distress call while crossing the Caribbean. More than 300 people disappeared with it, the single largest non-combat loss of life in U.S. Navy history.

No wreckage has ever been found. Storm? Structural failure? Something stranger? The sea has kept its mouth shut.

This line gets repeated a lot because it’s shockingly true. With sonar mapping still incomplete and most of the ocean floor left untouched by human eyes, researchers say we’ve charted only about a quarter of it in detail.

Mars, by contrast, has been mapped in full thanks to satellites. The ultimate plot twist is that we might understand another planet better than our own.

Decoding

Being a "treasured guest" is not a compliment. This is the hidden meaning

Have you ever heard "Code Adam" while shopping for groceries at Walmart? Or maybe you’ve heard how "Dr. Firestone" was being paged during a routine hospital visit. They sound like harmless announcements. But behind these ordinary words are secret codes staff use to signal emergencies without causing panic. From hospitals and supermarkets to airports and Disney Parks, these phrases quietly warn employees that something is happening. You hope you never hear them, but if you do, it helps to know exactly what they mean.

We all love getting special attention at airports or hotel desks, but if you hear the clerk call you a "treasured guest," don’t feel so flattered. You may not be as VIP as one could think.

In the hospitality industry, "treasured guest" has become a humorous bit of industry folklore to describe someone causing trouble. Maybe a customer yelling at staff over expired coupons, demanding impossible accommodations, or throwing a full-blown tantrum at the front desk. Whatever it is, the phrase has become the staff’s secret way to warn co-workers without escalating the situation in front of the customers. Most guests don’t realize the meaning, but once you know it, you may start hearing it more often. We just hope it’s not about you.

Imagine you’re pushing a shopping cart through Walmart when suddenly the overhead speaker announces, "Code Adam." You can easily assume it’s some kind of employee meeting or cleanup request. But when you see them start locking the exits and moving around, you know something’s wrong.

This code was created in 1994 by Walmart in collaboration with the National Center for Missing & Exploited Children (NCMEC), in memory of the tragic case of 6-year-old Adam Walsh. Adam was abducted from a Sears department store in 1981 while shopping with his mother. His father, John Walsh, later became famous for hosting the TV program America’s Most Wanted and advocating for missing children. Even if Adam’s story ended in tragedy, Walmart created the emergency system in Adam’s memory, and other retailers soon adopted it nationwide, intending to have a quick response to missing or abducted children.

You’re sitting in a hospital waiting room during a routine check-up when you suddenly hear "Code Blue, Room 214." Most people immediately know it sounds serious, even if they are not entirely sure why.

The phrase "Code Blue" is used at hospitals to draw the necessary staff and equipment to perform a resuscitation. It was created in the early 1960s at Beathany Medical Center by Dr. Hughes Day. Before then, hospital resuscitations were often chaotic and poorly coordinated. In 1961, Dr. Day received a grant to build one of America’s first cardiac care centers, and he developed both the Code Blue alert system and the modern crash cart to improve survival rates during cardiac emergencies. Today, the system is used in hospitals across the country, sometimes with specialized versions like "Code Blue Pediatric" or "Code Blue Neonate."

Imagine visiting a loved one in the hospital when the intercom calmly announces, "Paging Dr. Firectone to the third floor." Your head surely goes, "Dr. Firestone’s probably having a busy day up there." He is, but it’s not what you think.

The phrase is actually a discreet fire alert used to warn staff about smoke, flames, or overheating equipment without frightening patients and visitors. Hospitals adopted these coded announcements after realizing that openly yelling "fire" over loudspeakers could create panic, especially among patients who aren’t able to move quickly. "Code Red" is an alternative used by many health centers today, but it also hints at the situation while keeping hallways calm.

You’re standing at a checkout counter when the cashier picks up the phone and quietly says, "I need a Code 10 authorization." If you think that’s just another way to get a supervisor’s approval or technical issue, think again. In reality, the cashier may suspect the credit card is stolen or fraudulent.

Code 10 was developed through a cooperative effort between major credit card companies like Visa and Mastercard, along with international standard organizations. As credit cards became more common in the 1960s and 1970s, stores needed a discreet way to alert banks about suspicious activity without directly accusing customers and potentially putting employees at danger. When a cashier requests a Code 10, the bank’s operator begins asking yes-or-no questions to assess the situation and guide the employee on what to do next.

You’ve probably experienced those long airport security lines. The wait is usually uneventful. But sometimes, you can hear "Code Bravo" over the speakers. Maybe it’s a delay, or maybe it’s an issue with luggage. Within seconds, people stop moving, the security line freezes, and exits may even close. It’s something bigger.

Code Bravo is the emergency phrase used by airport security and the Transportation Security Administration to signal a serious security threat, such as an unattended bag, a breach at a checkpoint, or someone slipping into a restricted area. The term comes from the international phonetic alphabet used in aviation and military communications, where "Bravo" represents the letter B. When this is called, security staff immediately lock down affected areas, stop screening lines, and search for the source of the threat. To passengers, it’s sudden and confusing, but to security, it’s a carefully rehearsed response.

You are heading back to your cabin on a cruise ship when the speakers announce, "Code Alpha, Deck 7." You may think Alpha is related to the captain, but that’s not the case. It means someone on board is suffering a medical emergency.

The phrase comes from the NATO phonetic alphabet, where "Alpha" represents the letter A. In maritime emergency jargon, it became shorthand for a Priority A medical situation requiring immediate response. Cruise lines such as Royal Caribbean and Disney Cruise Line commonly use the term, though some ships use variations like repeating "Alpha" three times. Once the code is announced, onboard medical teams rush toward the specified deck or cabin. If necessary, stretcher crews are mobilized, and in severe cases, the ship may even divert course toward the nearest port for emergency evacuation. Passengers are enjoying the views, but the staff is running to save a life.

Anyone who remembers the CB radio craze of the 1970s probably smiles when they hear "10-4." Movies, truckers, and radio fans turned those number codes into a part of American culture. So if you overhear "10-33" on a police scanner, you might assume it’s just another routine message. But it’s not as simple as it sounds.

The 10-code system was first created in 1937 by Illinois State Police communications director Charles Hopper and later standardized by the Association of Public Safety Communications Officials, better known as APCO. Officers needed short phrases they could understand clearly over crackling radio signals. The 10-33 code commonly means an officer needs emergency assistance. In some departments, it also signals radio silence so dispatchers can focus on the crisis unfolding in real time.

Disney World is amazing, the parks offer something for everyone, and there are things to see wherever you look. But that’s exactly the kind of place where a child can easily disappear into a sea of strollers, balloons, characters, and crowds. For that reason, Disney has developed the "Signal 70," which alerts cast members and security that a child has become separated from their family.

The number comes from older police and emergency radio systems, where "70" was commonly associated with missing persons. Disney adopted the phrase because it allows employees to communicate discreetly without frightening or alarming nearby guests. If a member finds the child, they gently -and magically- escort them to Baby Care Center, where they coordinate the reunion.

Cruises are great to relax, enjoying a good book under the sun with a nice drink by the side. Until you hear "Echo, echo, echo" on the speakers. If you do, something is happening somewhere else on the ship.

The code is used among cruise employees to signal that dangerous winds or a navigational hazard are affecting the ship. It comes from the international maritime phonetic alphabet, where "Echo" stands for the letter E. In maritime signalling, the letter traditionally means "I am altering my course to starboard." And, in time, the phrase became associated with urgent ship maneuvers and weather-related warnings. However urgent, the repetition of the word by three doesn’t represent life-threatening situations. It alerts the crew of a certain hazard to prepare while avoiding panic among passengers.