Tintorera

Tintorera is a 1977 MexicanBritish horror film directed by Ren Cardona Jr and starring Susan George, Hugo Stiglitz, Fiona Lewis and Andrs Garca. It is based on the novel of the same name by oceanographer Ramn Bravo that studied the species of shark known as tintorera a 19ft shark and discovered the sleeping sharks of Isla Mujeres. The film, along with many monster movies of the 1970s and 1980s is very similar to Jaws. It is also known by the alternative title Tintorera Killer Shark.

The next day, Steven confronts Miguel in the hotel bar. Miguel tells Steven that Patricia was in love with Steven but she must have returned to England. Neither Steve or Miguel ever learn about her true fate. Miguel introduces Steven to two sisters, Kelly and Cynthia Madison Jennifer Ashley and Laura Lyons who are American college students who have arrived on the island resort for some fun. They have a double date and, on the sisters suggestions, swim to the yacht for some skinnydipping. The sharks heavy, labored breathing can clearly be heard but they make it to the boat safely. Kelly and Cynthia hop back and forth between Miguels and Stevens beds. They all swim back to shore the next morning and the submerged tiger shark again chooses not to bother them.Miguel encourages Steven to live a carefree, womanizing life like he does. Steven agrees. They even start a shark hunting business, swimming out to sea and shooting whatever swims past them, from local blue sharks to lemon sharks. Miguel tells Steven that if a tiger shark ever appears, they must immediately get out of the water because tiger sharks or tintoreras are too dangerous to even attempt to hunt. ........

Source: Wikipedia