The islands formed over millions of years. Tiny sea creatures called corals built up layers of limestone on the ocean floor, and over a very long time the land slowly rose until the tops of those limestone mounds poked above the water. Rain and waves then carved the soft rock into the rounded mushroom shapes you see today.
Inside the lagoon the water is so clear you can see the coral and fish far below even from a boat. More than 385 species of coral and 1,300 species of fish live here — making it one of the most colourful places on Earth under the water. Sea turtles, sharks, and rays glide between the islands every day.
The Rock Islands are also full of hidden caves, secret beaches, and bright-blue marine lakes cut off from the main lagoon. Some of those lakes have their own unique animals found nowhere else on the planet. Palauans have lived near these islands for thousands of years and think of them as a living part of their culture, not just scenery.