From the prison, head west / northwest and you'll come to an uncharted island. Follow the arrow that appears on the island until you get to the 4th island. As you land on the island, it will disappear and you see a giant Easter Bunny come up out of the water.

Do the same thing as above but, when you get to the first island, turn around and go south. You'll find another secret island. Climb up on the rock with the opening before the island and look to the west in the water and you'll see a baby Loch Ness Monster briefly.

Further to the south you'll find another island with dinosaur bones.

Even more to the south you'll find Shipwreck Cove Island.