Vickie and I recently sailed on the Disney Magic. Many Hidden Mickeys were lost during the "reimagining" of the ship, but (thank you, Imagineers!) many new Hidden Mickeys appeared! Some of the best new ones are in Disney's Oceaneer Lab on Deck 5 midship.
I checked when "Open House" was scheduled for the youth clubs, so I could enter and take photos to my heart's content! Paintings adorn the walls of the Oceaneer Lab, and many of these paintings contain subtle Hidden Mickeys. I'll start at the rear of the Lab, just as you enter from the special walkway that connects Oceaneer Lab to Oceaneer Club (both areas have the same age requirements: 3-12, so kids can run back and forth between the two areas as they like.) This classic (three-circle) Hidden Mickey is in a painting on the right wall as you enter the Lab. It's on a gold coin in a pile of treasure in a wrecked ship with sharks swimming in the background.
Turn left along the wall at the main entrance to the Lab and check out two paintings with Hidden Mickeys. The first is on the figurehead on the front (prow) of a sailing ship:
The second painting on this wall has a classic Hidden Mickey on an upper button of the sailor lady's (Captain Mary Oceaneer?) uniform. A parrot is perched on her shoulder.
On the wall opposite Captain Oceaneer is a painting of a ship with decorative gold on the bow and stern. Mickey hides in the swirls of the stern ornamentation.
At the rear of the Lab is a painting of a lady pirate with her sword drawn. She slams her boot down on a dining table and knocks off a plate of food. As the plate falls from the table, three green peas form a classic Hidden Mickey!
Be sure to check everywhere on the Disney Cruise Ships for Hidden Mickeys! The friendly Cast Members will help if they can; Happy Hunting!