The hand-held profiler principally contains light sensors, a fluorometer to measure chlorophyll in plants and a sensor to measure turbidity – the amount of tiny debris particles floating in the water. The CLIVAR cruise researchers deploy the instrument from the stern, or back end of the ship. In order to do this, the ship slows down so that the crew can carefully lower the profiler into the water. Credit: Cassandra Lopez, Rosenstiel School of Marine and Atmospheric Science, University of Miami