The coolest buddies in the world are back! The Ice Age is coming to an end and the glacier is melting fast, which means amazing water parks and endless fun. But when Manny, Sid, and Diego learn that the melting waters threaten to drown their home valley, a race against time begins.
Along the way, Manny is surprised to discover that he isn't the last of his kind – he meets Ellie, a mammoth who thinks she's an opossum! Also joining the adventure are, of course, the mischievous opossum brothers Crash and Eddie, and the eternal opportunist Scrat, whose acorn hunt reaches new epic proportions.
