Coral reefs are among the most diverse ecosystems on the planet. A typical reef is home to hundreds of species of fish and invertebrates. But what makes this life possible is the coral. The world's reefs were built by living coral. Over time, millions of corals build up the reef layer by layer. It is ironic that these gigantic structures are built by such tiny creatures. The images in this gallery have been hand-selected by Sea and Sky for their visual beauty and represent some of the most amazing images of coral reef life. Click on an image above to begin a slide show. Use the buttons under each image to navigate through the slide show. You can use the buttons on the left side of this page to select another image gallery and begin a new slide show.