Daniel Turmoil 
The Blue Hole [EPUB ebook] 
Uncharted Water, Two Entered, One Returned. A True Story of Two Divers Journey Into Darkness.

Located five kilometres northwest of Dolly's Cave in The Bahamas, there exists a dark blue opening within the coral reef. This particular opening is known as the Four Sharks Blue Hole, and it harbours one of the largest underwater caverns in the entire region at its depths. Upon entering this cave and venturing towards its furthest point, one will come across a narrow crack in the rock, leading to an almost inaccessible yet incredibly vast chamber. It was during the year 1997 that two individuals, Rob Parker and Dan Mallone, also known as Duffer, found themselves exploring this uncharted and unexplored section. Unfortunately, their expedition took a horrifying turn.