Lost Cities, Shipwrecks, and Skeletons
The Fury and Helca Straight Noise

Credit: icarmen13/Shutterstock
Near the frozen waters of Canada, The Fury and Helca Straight was known for tundra wildlife and small hunting/fishing communities, until a strange humming and pinging noise started charging through the waters scaring off wildlife. You can only hear the completely unknown noise as it reverberates through the hulls of ships. Some fisherman are going deaf because of it.
Heracleion, The Lost City

Source: YouTube @fridaykiss
Heracleion was an ancient Egyptian port city thought to be simply lost to time and the elements, never to be found again. It was written about in many ancient texts, but no evidence of it had been seen for thousands of years. That was until archaeologist Franck Goddio decided to dive down into the sea where he finally found the underwater ruins of the city after four years of searching.
Sea Blob
In 2012, a worker on a Gulf of Mexico oil rig was inspecting the underwater portion of the construct with his remote-controlled camera when he happened upon a strange, humungous creature. The big, brown, fleshy thing kept hanging around the rig like it loved the camera.
It turns out it was a jellyfish called the Deepstaria engimatica. The creatures are very mysterious because they live in deep water and are just too big to be taken in for studying.