Sanya Bay

Wikpedia says that the meg's final attack is at the beach at Sanya Bay, which in real life is at Sanya City, Hainan island, China.

And no doubt someone can probably find maps the bay which show the depths of the bay at various points.

At one point there is an aerial shot showing hundreds or thousands of swimmers headed for the beach. And the shark can be seen underwater. It seems to turn around and head back out when at a distance of only about 100 feet from the shoreline.

In earlier shots when the shark was swimming under the humans completely submerged it could be seen through the water. At this point the swimmers were presumably hundreds of feet farther out from the shore where the water was deeper. And as the shark passed under people it seemed to about 15 or 20 feet wide. Which means its torso should have been about 15 or 20 feet talle, plus the dorsal fin that was probably about 6 feet high.

So even if the shark's belly was touching the sandy bottom, the water depth would have to be 20 to 26 feet for the tip of its fin to be hidden underwater instead of showing above the water.

The mother of the plump little boy told him not to go where it was dangerous. And later he was one of the many people headng for the shore in terror. And in one scene the magaldong looking like it was getting close to him and he would be eaten. So apprently he paddled out to water which was 15, 20, or 25 feet deep.

And apparently the megaladon was only about 100 feet from the shore when it turned around, and yet seemed to be totally submerged. So the bottom of the bay would seem to slope quite steeply at that bathing beach. Which doesn't seem too safe to me.