Lusca
From AmericanMonsters.com:
These vicious, half-shark, half-octopus man-eaters are said to have inspired terror amongst fishermen and scuba divers in and around the blue holes of the Bahamas for decades.
The island of Andros in the Bahamas is the home to a spectacular array of what the natives refer to as blue holes. Formed during the ice ages of the last million years or so, these blue holes are a vast network of underwater cave systems which link the Andros’s small freshwater lakes with the Atlantic Ocean.
Ironically, the confirmation of this oceanic passage has lent some credence to the legend of a HYBRID-BEAST, which is said to dwell in these blue holes… a legend known to locals as the Lusca. These ferocious octo-sharks have been described as being 75 to 200-feet in length, with the razor sharp teeth of a shark and an array of octopi-like multi-suckered tentacles.
Although the few eyewitnesses who have survived Lusca attacks seem to agree that the above description is accurate, there are others who insist that this animal’s appearance incorporates more of a “squid-eel” combination. Either way, the result is a terrifyingly voracious predator, which one can only assume is equally horrifying in appearance.
Often believed to be an unknown species of cephalopod like the KRAKEN, the FRESHWATER OCTOPI or Octopus Giganteus (akin to the now infamous ST. AUGUSTINE PHENOMENON,) these large, sub-aquatic anomalies have inspired terror in the hearts of generations of Bahamian fishermen.
Legend has it that any encounter with this extraordinary beast almost always results in the death of whoever was unfortunate enough to wander too close to its watery lair. This extends not only to intrepid divers who have dared to brave the labyrinthine depths of the blue holes, but also to those unwary souls who stand too close to the shoreline, as the Lusca — much like the AHUIZOTL and EL CUERO — has been known to use its tentacles to drag even earthbound victims to their watery graves.
Onlookers have even described seeing fishermens’ boats suddenly being yanked below the surface of the blue holes, only to watch in horror as the indigestible flotsam of these broken vessels slowly raises to the surface, their captains and crew nowhere to be seen.
This description of a purported Lusca attack has led some oceanographers to suggest that what people are mistaking for this legendary creature’s voracious appetite may, in fact, be a natural oceanic phenomenon caused by swift tidal changes which suck the water back in through the blue holes, resulting in a spontaneous whirlpool.
These sudden whirlpools roll and boil, and almost certainly hold the potential to pull unwary swimmers, or even entire boats, into its churning depths. When the currents reverse, a frigid, mushroom cloud-like surge of water is gushed back into the small lake, which could force the wreckage to the surface.
While this theory may apply to some cases of mysterious blue hole disappearances it in no way accounts for the colossal tentacles and shark-like visage described by eyewitnesses.