In this laboratory activity, students investigate chromophoric dissolved organic matter (CDOM) through gradual dilution of black, green and chamomile tea. Through this activity, students discover how CDOM can dominate the absorption of sunlight, how sunlight degrades CDOM through photochemical oxidation, and how CDOM levels are related to nutrient status, stratification and mixing of the ocean. Materials needed include coffee mugs, hot water, spoons, and tea. This resource is found in Rising Tides, a journal created for teachers and students reporting on current oceanography research conducted by NASA, NOAA, and university scientists, featuring articles, classroom activities, readings, teacher/student questions, and imagery for student investigation of marine science.