The name Rarotonga means "in the direction of the prevailing wind, south," the place where the chief of Atiu promised early explorers they would find an island. It's fairly small, just 31 km around.
Twisting valleys lead up to steep ridges covered with luxuriant green vegetation and towering mountains crowned in clouds. Yet, Te Manga (653 meters) is only a fraction of the height Rarotonga reached before the last volcanic eruption took place, more than two million years ago.
Though Rarotonga is younger than the other Cook islands, continuous erosion has cut into the island, washing away the softer material and leaving the hard volcanic cones naked. The mountains are arrayed in a U-shaped arch, starting at the airport and then swinging south around to Club Raro, with Maungatea plopped down in the middle. Together they form the surviving southern half of the great broken volcanic caldera that became Rarotonga.
The reef circling the island defines a lagoon that is broad and sandy to the south, and narrow and rocky on the north and east. The finest beaches are on the southeast side near the Muri Lagoon, with crystal-clear water and a sandy bottom, but the best snorkeling is at Titikaveka. Elsewhere the water can be cloudy or shallow, with a lot of coral and shells that make wading difficult. Take care everywhere, as several snorkelers have drowned after being sucked out through the passes where a lot of water moves because of surf and tidal swings.
Scuba diving on Rarotonga features coral drop-offs, canyons, caves, walls, sharks, wrecks, and swim-throughs. All beaches on the island are public.