Plot
Scrat inadvertently causes the break up of Pangaea. Meanwhile Manny and Ellie must deal with the trials and tribulations of their daughter Peaches, now a teenager desiring to fit in with her peers. Ellie is fine about that, but Manny becomes extremely over-protective. Peaches' only friend is Louis, a molehog, tries to protect her as she tries to approach a mammoth named Ethan whom she has a crush on. Sid's family returns, only long enough to drop off the elderly Granny before abandoning them both again. When Manny catches Peaches sneaking off to meet Ethan, they argue and fallout. Shortly afterward, a continental break-up separates Manny from the herd. Trapped on a moving chunk of ice with Sid and Diego, Manny has no choice but to ride out the current. Meanwhile a giant land shift encroaches on Ellie, Peaches, and those remaining on land, causing them to make their way toward the land bridge.

At sea, violent weather pushes Manny and the others further away from land while Scrat, in a side adventure, finds an acorn that has a treasure map on it that directs him towards an island. Soon, after Manny, Sid, and Diego find Granny (who was sleeping inside a hollow tree stump, on the ice raft), they are captured by a band of pirates sailing on a floating iceberg as a ship led by a Gigantopithecus, Captain Gutt, who attempts to press gang them into his crew; when they refuse Gutt tries to make them walk the plank. Manny, Sid, Diego, Granny and Scrat (who was also taken captive) escape, but cause the ship to sink and Gutt's first mate, a female sabertooth named Shira joins them out of no choice of her own.

They then find Switchback Cove, which has a current that would direct them home, but after washing ashore a remote island, Shira escapes and tells Gutt and the pirate crew (who are also on the island) of their whereabouts. Gutt, wanting revenge on Manny for sinking his ship, plans an attack. Along with the hyrax inhabitants of the island, Manny coordinates a plan to steal Gutt's new ship to return home. Shira decides to leave Gutt, when she and Diego begin to fall in love, but she stays behind to ensure Gutt doesn't catch the herd. Gutt and his pirates quickly make a new iceberg ship to sail after the herd, determined to get revenge. Meanwhile, Scrat, using one of the hyrax's leaf "planes", flies off the island, only to be swallowed by a shark.

Peaches finally begins to fit in with the mammoths her age, but accidentally insults Louis, who is referred to as a freak by the others, by saying they are not friends. When she sees the other teens' careless disregard to the danger, she turns her back on them, warning that their extinction will come sooner than they think.

As they are sailing back, Diego, Sid, and Granny encounter monstrous sirens taking the shapes of what the group finds most attractive. Fortunately, Manny realizes this after hearing a siren, disguised as Ellie tell him something she would never say and saves them at the last second. Later, Scrat encounters a siren, taking on the shapes of Scratte (that Scrat ignores) then an acorn. Scrat immediately runs up and attempts to bury the "acorn", but is attacked by other sirens and escapes unharmed.

Manny, Sid, Diego, and Granny soon return home only to find the land bridge destroyed in the earthquakes and Gutt and his crew made it there first and have captured Ellie and Peaches. Louis stands up for Peaches and a battle ensues between the herd and the pirates. Shira frees Ellie and helps fend off her former comrades, while Granny's previously unseen (and claimed imaginary) pet whale, Precious, appears and turns the tables on the rest of the lot. Gutt then attempts to kill Ellie but Peaches, using her possum-like skills, manages to save her. Manny defeats Gutt in a duel and reunites with his family and friends. Later, Gutt encounters a siren taking on the shape of a female of his species and is eaten. With their home destroyed, the entire party and inhabitants then sail to an island that they found to settle down, while Louis becomes a hero among the teenage mammoths and Shira joins the herd and becomes Diego's lover.

At the end of his journey, Scrat discovers the island on the map, know as Scratlantis (a mock up of Atlantis), but his uncontrollable urge to hunt acorns in the acorn-rich city inadvertently causes the entire island to sink and Scrat is ejected into what is now known as Death Valley.

Critical response
Ice Age: Continental Drift received generally mixed to negative reviews from critics. Review aggregator Rotten Tomatoes reports that 37% of critics have given the film positive reviews, with a rating average of 5.1/10 based on 131 reviews. The consensus statement reads, "Ice Age: Continental Drift 3D has moments of charm and witty slapstick, but it often seems content to recycle ideas from the previous films." Another review aggregator, Metacritic, which assigns a normalized rating out of 100 top reviews from mainstream critics, calculated a score of 49 based on 29 reviews, indicating "mixed or average reviews."

Roger Ebert of the Chicago Sun-Times gave the film two stars out of four, calling the film: "Watching this film was a cheerless exercise for me. The characters are manic and idiotic, the dialogue is rat-a-tat chatter, the action is entirely at the service of the 3-D, and the movie depends on bright colors, lots of noise and a few songs in between the whiplash moments." Megan Lehmann of The Hollywood Reporter said: "It's familiar, drawn-out shtick, and the humor lacks the subtlety of the first and best Ice Age, but there are some visually inventive high points." Simon Brew, writing for Den of Geek, gave a very positive four-star review, saying that "not only is Ice Age 4 arguably the best in the franchise yet, it's also, a little surprisingly perhaps (given that it's a fourth movie in a franchise, turned around on a strict cycle), turned out to be thoroughly, thoroughly entertaining family blockbuster."