This is the Megalodon. I created this cryptid creature / monster art for Fairytales and Myths.
The megalodon was a giant shark species that lived 2.6 to 23 million years ago, inhabiting the warm oceans of the world. However, there have also been purported sightings in more recent times.
The main issue with creating artwork about the megalodon is expressing the sheer scale of the creature. It’s a giant shark, but unless you give context clues it looks like any other shark species when swimming alone. I decided to have the meg chasing down some dolphins while a submarine is in the background. Pardon me if the sub is not technically accurate; I made up its design without using a real reference.
Check out the Megalodon page for more details.