A coral reef is like an underwater city built by tiny animals called coral polyps. Each polyp is smaller than your fingernail, but millions of them working together for thousands of years build enormous, colourful structures that become home for fish, sharks, rays, turtles, and seahorses.
The reef around Roatán is part of the Mesoamerican Barrier Reef System, which stretches all the way from Mexico to Honduras. It is so long you could drive along it for nearly two hours at motorway speed! It is second only to Australia's Great Barrier Reef.
In the clear, warm waters around the Bay Islands you might spot sea turtles gliding past, spotted eagle rays flying through the water like birds, parrotfish crunching on coral (they make a lot of sand by doing so!), and shoals of blue tang - the same type of fish as Dory in Finding Nemo.
The islands themselves are covered in tropical forest, with small colourful wooden houses on stilts near the shore. People on Roatán speak English as well as Spanish, because the islands were part of British Caribbean history before becoming part of Honduras.
Because the reef is so precious and fragile, people work hard to protect it. Sunscreen chemicals can harm coral, so special reef-safe sunscreen is used by visitors, and fishing rules help keep fish populations healthy.