In the sunlit surface of the ocean, primary producers convert carbon and other elements into organic matter, which serves as food for microbes. While most of this newly formed organic material is quickly respired, a small fraction somehow evades this process and persists as dissolved organic carbon (DOC) for thousands of years. This vast carbon reservoir plays a crucial role in carbon sequestration and climate regulation. However, despite decades of study, key questions regarding the production, transformation, and long-term fate of DOC remain unresolved. In this talk, I will provide an overview of my current research, which explores some of these critical aspects.