In recent years, fishermen in the Sea of Cortez have reported seeing a shark of truly frightening proportions. This creature is reported to be 20 to 60 feet long, .br br In Search of Mexico's 60 foot Black Demon Shark HD - Demon Shark Documentary The Black Demon Shark is said to be an enormous black shark off the cast of .br br At least one expert disagreed with the timetable for megalodon extinction. In 1872, the HMS Challenger conducted a four year scientific expedition dredging and .br br In recent years, fishermen in the Sea of Cortez have reported seeing a shark of truly frightening proportions. This creature is reported to be 20 to 60 feet long, .