The purpose of the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) Project is to provide quantitative data on global ocean bio-optical properties and to assess the oceans' role in the global carbon cycle. SeaWiFS data are being used to help clarify the magnitude and variability of chlorophyll and primary production by marine phytoplankton, and to determine the distribution and timing of spring blooms, i.e., the time of highly abundant growth. The orbiting sensor can view every square kilometer of cloud-free ocean every 48 hours. As such, the satellite-acquired ocean color data constitute a valuable tool for determining the abundance of ocean biota on a global scale and can be used to assess the ocean's role in the global carbon cycle and the exchange of other critical elements and gases between the atmosphere and the ocean.