Red Tide?

During diving, there were different probabilities that one would encounter the sea current, depending on the diving location. As the name suggested, the descending current was also known as the down-current. Supposedly, the air bubbles exhaled from the diver's mouth would ascend to the surface of the sea. However, if there were currents around the divers, their air bubbles would disperse around them in a ring shape. After that, the air bubble would drag to the bottom of the ocean by the down-current. The two turtles not far away could sense that something was not right. So, they quickly swam back to the crack between the rocks. And at the same time, the three's vision began to become blurry.