Each year marine phytoplankton extract enormous quantities of carbon dioxide, nutrients, and minerals from the atmosphere and ocean to manufacture the proteins, carbohydrates, and lipids needed to sustain life. Microbes are continually reorganizing elemental cycles to meet their metabolic needs, sometimes working with and sometimes against, physical and geological forces. Regional and local variations in climate yield a diverse community of marine photoautotrophs, highly attuned to their environment. At the molecular level, this diversity and tuning is expressed in the system’s genome. Genes direct the synthesis of organic chemicals, and the diversity we observe in the marine microbial genome is the source of an equally diverse suite of organic chemicals present in seawater as dissolved organic matter. Dissolved organic matter includes essential vitamins, substrates, organonutrients and siderophores that limit both primary and secondary production, redox sensitive organometalic compounds that affect biological uptake of important trace metals, and quorum-sensing organic compounds that may shape community-wide metabolism. Understanding which organic compounds are present in the environment and how they affect biogeochemical cycles is a still largely unexplored approach to understanding marine microbial diversity and metabolism. The SpecDROM website is a spectral database of mass and visible spectra for dissolved organic compounds isolated from pure cultures and environmental seawater samples.