The Bay Islands are made up of 8 large islands and 53 smaller islets situated on the southern tip of the Mesoamerican Barrier Reef – the second largest barrier reef system in the world. The Islands here are a popular tourist destination and amongst the most famous diving destinations anywhere in the Caribbean. This expedition combines research at two of our leading marine research sites on the islands of Utila and Roatan to form a project fully focused on tropical marine ecology. While Utila is home to largely unmanaged reefs and a booming low-cost tourism industry, the reefs of Roatan have been well managed by the Roatan Marine Parks Authority. Working at both sites gives contrasting views of the state of Caribbean coral reefs, allowing us to improve our understanding of how these vital ecosystems function in a changing world.