You need to visit the underwater world of Neptune and complete several missions to help Scooby Doo visit the den where the shark lives. To do this, you need to use the bathyscaphe and go down to the bottom of the ocean on it. There you can collect a lot of items that will help you then in the game. After all, the goal of the game will be that you will need to solve logical puzzles, and find a way out of them. In each level, you will face new challenges that you will face. But don't swim very close to the sea monsters that live in Neptune's lair. You can pick up some along the way and then use them to open the doors.