Coral might look like a colourful rock, but it is actually millions of tiny animals living together. Each one is smaller than a grain of rice. Over hundreds of years, they build huge underwater cities called reefs, where fish, octopuses, turtles and seahorses come to live.
The Coral Triangle has more than 600 types of coral and around 2,000 kinds of fish. That is more than anywhere else on Earth. If you put on a snorkel and a mask and looked down off a Philippine beach, you might see clownfish like Nemo, parrotfish that crunch on coral, and giant clams the size of a dinner table.
One of the most magical visitors to Philippine waters is the whale shark - the world's biggest fish, but completely harmless. They glide through the warm waters with their huge mouths open, sipping in tiny plankton. In a town called Donsol, snorkellers gently swim alongside them in the wild.
Coral reefs are very important. They are nurseries for baby fish, they protect coastlines from big waves, and they give millions of people food and jobs. Filipino schools and fishing communities work together to keep their reefs healthy: planting new coral, banning fishing in certain areas, and teaching kids to look but not touch.