As in the previous films, the main protagonists are the mammoth Manny, the sloth Sid, sabre-toothed cat Diego, and, in a parallel storyline, the saber-toothed squirrel Scrat. Scrat's hunt for acorns triggers the break-up of the Pangaea continent into the continents as we know them today. In the meantime, Manny and his wife Ellie deal with their teen-age daughter Peaches who has a crush on Ethan. The breakup of the continent separates Manny from his family. Manny gets stuck on a floating ice raft together with Sid, Diego, and Sid's grandmother Granny. A large moving landmass drives Ellie, Peaches, and a herd of other animals towards a land bridge, where they hope to reunite with Manny.
Manny and his friends are captured by a pirate gang led by a giant ape named Gutt, who are sailing the oceans on a large ship-shaped iceberg. They manage to escape, in the process destroying the pirate ship, and again float on the oceans on a small ice raft. They rescue the female pirate saber-toothed cat Shira, who reluctantly joins the group. After the group reaches an island, Shira escapes and rejoins the pirates, who are building a new ice ship elsewhere on the same island. The protagonists overtake the new ice ship and sail away, with the help of a large number of hyraxs, and Shira, who changed her mind after being threatened by Gutt. Gutt quickly turns a new iceberg into a ship, propelled by sharks, and chases Manny's gang.
