The deep waters around and off the coasts of the Belizean cayes and atolls are among the least studied areas of the Caribbean Sea. The 2014 Nautilus cruise to the western Caribbean will conduct seafloor mapping and ROV exploration of the areas around and offshore the cayes and atolls of the Belize Barrier Reef, including potential mud volcanoes off Turneffe and Lighthouse atolls. Additionally, archaeological survey will be conducted with side-scan sonar and ROVs in areas of historical importance around the Belizean cayes. The Gulf of Honduras in the western Caribbean is home to large and abundant deep-sea coral and sponges. This is a dilution basin where sediment from rivers is mixed with the surrounding ocean waters. The two reef systems comprise the southern half of the Mesoamerican Reef, comprised of lagoons, coral reefs, barrier reefs, and atolls. This reef system is a World Heritage site and is listed on the UNESCO List of World Heritage in Danger. The deep areas of these reefs and atolls have never been explored or mapped and hold a great potential for understanding the dynamics of this bay and the health of the reefs.