8 Sunken Objects is a mission of the Great White Shark in Hungry Shark Evolution. To complete this mission, you must use the Great White Shark to find eight sunken objects in a single gameplay session. The reward for completing this mission is 2,000 coins. Find the Toy Robot, Teddy Bear, Dart Board, Bog Brush, Clockwork Robot Gibbon, Leaning Tower Of Pisa, Lucky Horseshoe and Shark of the Covenant. (If you are down in the eastern cave, the Kempy Cave with Framed Picture of an Egg is also a good choice.)
Generally speaking, the Great White shark has enough stamina (a good enough health bar!) to find all 15 objects. Since there is no reason to risk one's life, however, the Jade Dragon or Wakaba seem feasible, if one were in that area, but there will hardly be a reason to go for Moon on a Stick or False Teeth.
There is a video of a Megalodon finding all 8 objects. You can use the video as a guide.