Just over 70% of the earth's surface is covered by the ocean. So far, people have only researched about 5% of it in 2020. Imagine what may be out of our reach: types of depth that we have not yet encountered, or a lost megalodon from prehistoric times. Maybe a long-lost shipwreck or the lost city of Atlantis. Maybe something dark and disturbing, who knows? While we are waiting for the experts to explore the unknown, some puzzles need to be resolved below.
See also: 10 dark puzzles with strange cults
8 19th century shipwreck
On May 16, 2019 researchers aboard the Okeanos Explorer of the National Oceanic and Atmospheric Administration (NOAA) were in the Gulf of Mexico when a remote-controlled vehicle they were testing stumbled across a 200-year-old shipwreck.
A closer look revealed that the ship was built from wood with a copper jacket and would have been about 30 meters long before sinking. At this point, however, more questions than answers emerged. Archaeologists still don't know where the ship came from, how old it is, what happened to the crew, or what type of ship the ship is.
The only clue discovered at the time of the discovery was number 2109, the rudder and iron and copper objects were scattered nearby. Burnt pieces of wood indicated that the ship may have caught fire before sinking. After the discovery was released, NOAA's Frank Cantelas expressed hope that further expeditions would be undertaken to uncover the secrets surrounding the shipwreck. 
7 Mysteries Of The Black Sea
Formerly known as the Inhospitable Sea and the Hospitable Sea, the Black Sea is a treasure trove full of curios and secrets. Like the Bermuda Triangle, the Black Sea is the center for strange creature views, unexplained phenomena and bizarre disappearances. In 2000, Robert Ballard announced the discovery of evidence that people were killed in a huge Black Sea flood. This discovery was linked to the history of the Biblical Flood, as explained in the book of Genesis, and of course sparked a lot of controversy.
In the Middle Ages, Turks and Russians reported seeing whirlpools in the Black Sea that swallowed ships and islands. These whirlpools would appear to appear on calm water without any warning. This caused the fishermen to avoid the area because they considered it cursed.
Five Soviet bombers disappeared over the Black Sea in December 1945 so that they would never be seen again. A Greek plane also disappeared in 1990. This has led to the theory that there may be a magnetic anomaly that causes electrical malfunction. It is said that in 1991 a Russian oil platform was torn from its berths and driven out into the Black Sea. Investigations allegedly showed that all 80 employees were missing. Their abandoned possessions and half-eaten meals were the only evidence that they were ever on the platform. 
6 Namse Bangdzod
On December 27, 2018, the Namse Bangdzod, a 1,950-ton oil tanker with eleven crew members and a captain on board, set off from Sampit towards the Tanjung Priok Port in Jakarta. Their arrival was expected the following day. On December 28, however, all contact with the ship was lost in the waters of Ujung Karawang. The last data entry the officials followed was on January 3, 2019.
The National Search and Rescue Service of Basarna believed that the tanker may have been kidnapped by pirates. The Navy disagreed and said that the distance traveled by the tanker was considered very safe and there was no ransom demand. The Navy also claimed that the ship changed positions several times and sailed from Jakarta Bay to Sunda Kelapa Port, but was never found.
The marine expert, Oloan Saut Gurning, said an accident was highly unlikely due to the fact that no distress signal had been sent, and he did not believe that the tanker was floating at sea, as the Navy would have found in this case. Basarnas should continue to search the ocean for 4 days, after which the police and navy would do the search. The tanker is still missing today. 
5 Death Island
Koh Tao is an idyllic island located on the west bank of the Gulf of Thailand. Koh Tao means "turtle island" and its coral reefs are inhabited by beautiful marine animals including turtles. There are a variety of accommodation options here that benefit both price-conscious and luxury lovers. This place is a truly amazing vacation destination … at least superficial.
Its beauty and luxury cover a dark and unsettling core of criminal activity. Shady rumors of parts of the body floating in shallow water and the island controlled by the local mafia have been highlighted after a series of unexplained deaths. People are now careful to travel to Koh Tao or the so-called Death Island, and for good reason. Ben Harrington died in 2012 after his motorcycle hit an electricity pylon. He was the only one on the bike at the time and his wallet and watch were nowhere to be found after the accident. His mother believed he had been the victim of a tripwire crime, especially after the medical examiner did not find the cause of the death to be "accidental."
In September 2014, two backpackers, Hannah Witheridge and David Miller, were found murdered on the same beach, Ben Harrington had stayed before he died. Afterwards it became known that Hannah had been raped before she was killed. The local police were unable to secure the crime scene or monitor the island's port. Instead, they focused on barbecuing two Myanmar migrants who were eventually found guilty and posted the death penalty for the murders. However, officers reportedly failed to collect DNA samples and test victims' clothing. Another body was found on the same beach two weeks after the murders. 24-year-old Luke Miller was found on the bottom of a swimming pool.
23-year-old Valentina Novozhyonova disappeared from a Koh Tao hostel to never be seen again. A young girl's body was discovered six weeks later, but it wasn't Valentina. Instead, it was the remains of the Belgian tourist Elise Dallemagne. her body was burned and wrapped in T-shirts.
Christina Marian Annesley, 23, was found dead in a Koh Tao bungalow in January 2015. Her remains were kept in a temple for days before an autopsy took place. As a result, a British coroner rejected the Thai results for incompetence.
All of these unexplained deaths led to rumors of a serial killer family on the island or to the involvement of the local mafia. In any case, there is still no closure for the disturbed and destroyed families. 
4 A shipwreck and a curse
The HMS Wasp was built in 1880 for fishing purposes and lighthouse inspections. It also promoted bailiffs who cleared several places. The Wasp was very popular in Derry and visited the port here with its sister ship HMS Valiant. On September 21, 1884, the wasp was to sail to Moville to gather bailiffs and other personnel to clear Innistrahull Island. The route had traveled far and the mood was high.
Unfortunately, tragedy struck soon after. At 3:45 a.m., the wasp struck the rocks on Tory Island. It sank within 30 minutes. 50 crew members died, only 6 survived the accident.
Afterwards, a report from one of the survivors showed that when the wasp approached Tory Island, it was only sailing and its cauldrons were off. It should sail between the Tory light and the mainland instead of going around the island, which would have been safer. The survivor also claimed that all of the senior officers slept soundly and the junior crew took responsibility.
Nevertheless, most agreed that the accident was very strange, especially since the ship touched the rocks directly under the lighthouse. The water was calm and the weather was good. The Tory light shone brightly after the sinking, but opinions differed as to whether the light was on as the wasp approached the island. Some believe that the light was deliberately awarded to prevent the wasp from bringing bailiffs to the island. Others claim that the curse stone of the Tory was released on the ship, which ultimately resulted in disaster. An admiralty investigation gave no clues as to what exactly went wrong, and the demise of HMS Wasp remains puzzling. 
3 Mysterious Divers
Divers are not freed from paranormal experiences while exploring the depths of the ocean. Not only did divers hear the sound of boat engines starting while the sea surface above them was free of boats, but they also heard strange grinding noises from the engine room of the Japanese Hoki Maru ship that sank in the Truk lagoon in 1944.
In 2007, a group of divers explored the ocean around Grenada. After getting tired underwater, the group returned to their ship to look at each other's notes of what they had seen below the surface of the sea. A group member asked if his friends had seen another diver in a white shirt waving to their group. No one else had seen this mysterious diver and a head count was made to ensure that no one was missing. Everyone was considered and there were no other boats or ships in the area. The group never found out who the diver in the white shirt is.
In 2012, diving instructors dived in Santa Rosa, California when they spotted an unknown diver with a pink tank dive swimming near a blue hole. They swam closer to check if the diver was in trouble, but just before they could reach the hole, the diver disappeared. The diving instructor immediately reported to the police, who in turn informed them that the figure at the blue hole had appeared to other divers before it disappeared. 
A strange story that had long since been resolved into folklore, with several additions, is a strange boat that was washed ashore in Japan on February 22, 1803. fishermen who saw the boat claimed that it was round in shape with upper windows and metal strips on the bottom. They boarded the ship and found a lonely passenger on a wall littered with strange writings. The passenger, a young woman with red hair, was holding a box on her lap and could not understand the language of the fishermen. She also refused to let go of the box.
The incident was given the name "utsuro-bune / hollow ship", and at the time the fishermen believed that the woman could have been a princess who carried her dead lover's head in the box that held her so tightly , Not knowing what to do with her, they let the boat float with the woman at sea. They had never seen glass windows and strips of metal appearing on the boat before they came to the theory that the woman might have been an alien.
Others had no use for alien theory and instead believed that the red-haired woman was a spy from Russia. Nowadays, experts believe that the boat may have been covered with a dome to improve its seaworthiness and thus its rounded shape. So far, however, there has been no explanation or other theories about who the woman might have been and what she was wearing in the box and what the writing on the boat's walls meant. 
1 Sea monsters
Sea monsters in all shapes and sizes are legendary. It's hard not to feel a bit of a thrill when it comes to mentioning octopuses, colossal squids, or cannibal sharks. Stories about encounters with sea monsters have been around for hundreds of years. One of the better known stories is told by G. H. Hight and a companion who traveled to Madagascar in 1889 to be told by villagers about a giant green sea snake that had attacked a fishing boat and eaten one of its four residents. She chased the three survivors to the beach before disappearing into the sea. Hight also witnessed the snake after organizing a search party to search for the unfortunate fisherman who had been attacked by the monster. He and other men shot it, but to no avail. Of course, there is no evidence to support this story, and the only report of it appeared in the Washington Herald in March 1909.
Another troubling story was published in Fate Magazine in 1965. 16-year-old Edward Brian McCleary set off for a day at sea in the Gulf of Mexico with four friends in 1962: Warren Felly, Eric Ruyle, Larry Bill and Brad Rice. McCleary returned home alone, exhausted and frightened. He told the police that a sea monster / dragon had appeared in the water and attacked his friends and killed them. He described the monster as having a 12-foot neck, green scales, and an elongated head that resembled that of a turtle.
McCleary dismissed the claims that he thought a submarine was a terrible sea creature and continued that the news agencies refused to publish his story unless he omitted the story of the sea monster. Larry Bill's body was reportedly found (he had drowned), but the other three boys never were. Of course, very few believed the story of a sea dweller emerging from the depths to attack youth. It remains a mystery what exactly happened on this fateful day.