Scientists are excited about the Bahamas, and it’s not just the tropical vacations that have their interest. It’s what’s underneath the surface of the islands—huge caves systems filled with water. They’re called blue holes, and deep inside of them lie clues to past climate change, new species of invertebrates, even human remains from people who lived on the islands long before Columbus visited. In this podcast, hear from Kenny Broad, a researcher who led a diving expedition into blue holes last year. Podcast produced by David Levin. Original interview by James Barrat. NOVA is produced by WGBH in Boston. Music courtesy APM music and Universildo (freemusicarchive.org/music/Universildo/). Funding for NOVA is provided by ExxonMobil, David H. Koch, the Howard Hughes Medical Institute, the Corporation for Public Broadcasting, and public television viewers. To learn more, go to pbs.org/nova/cavedive