The world is full of unexplained mysteries, despite countless paranormal investigations and scientific searches aimed at uncovering the truth behind these phenomena. Like ghosts, spirits and haunted buildings, sometimes you simply can't explain these mysteries of modern life. Here are some of the most well-known.
Sky quakes
Even before flight was invented, booms have been heard blasting out all over clear skies around the world. These are now known as sky quakes, but no explanation has ever been given for them. They're not caused by lighting, but some people believe these sounds may be due to extra-terrestrial activity. Radio waves, solar activity and submarine activity have all been suggested to cause these booms, but no clear answer has been given.
Taman Shund
A creepy mystery close to home comes in the form of the Taman Shund case. It started with a man found dead on an Australian beach in 1948, with no clues on his person as to his identity. The only clue given was the words "Taman Shund" on a piece of paper in the pocket of his trousers.
These words were discovered to be Persian, meaning "finished" or "ended" and directed from a collection of poems written by Omar Khayyam. The physical poem was discovered in a car near the body, with the final page missing. To this day, the Taman Shund case has left many stumped.
SS Ourang Medan
The disappearance of the SS Ourang Medan from Malaysia has haunted many, and is perhaps one of the most fascinating mysteries in the history of ships. It all started with a 1947 SOS message that said the captain and crew were dead. The telegrapher then died during the message's transmission. The Silver Star went to inspect the ship and confirmed the deaths of all those onboard, but no explanation was given for their demise. Ghosts, aliens and hazardous chemicals are all options.