SCP-169 is a Keter-class anomaly and is one of the largest and most threatening SCPs from the SCP Foundation. It is a marine arthropod crustacean of enormous size, known as the "Leviathan" from generations of sailors throughout history. Unlike other lethal SCPs, Such as 682 and 049 that are contained within the Foundation, SCP-169 is incapable of being contained due to its size. The beast is estimated to be 2000 and 8000 km long. SCP-169 is also believed to have existed on Earth since the Pre-Cambrian era. In the year of 1997 the U.S. National Oceanic and Atmospheric Administration, unaware of the 

existence of the Foundation, detected an ultra-low-frequency extremely powerful sound in the south Pacific Ocean around the west point of the tip of South America that was made by SCP-169. The sound was named the Bloop. But confusing engough, the name is actually Leviathan.