Similes:
As happy as a beggar in a gale of wind.
As quiet as a mouse.
As cool as a cucumber.
As strong as an ox.
As brave as a lion.
As sly as a fox.
Metaphors:
The island was a treasure chest of secrets.
The ship was a ghost ship, crewed by skeletons.
The pirate captain was a one-eyed monster.
The buried treasure was a pot of gold at the end of the rainbow.
The search for treasure was a wild goose chase.