NASA's Surface Water and Ocean Topography (SWOT) platform monitors Earth’s surface water, collecting data to contribute to the first global survey of the Earth's surface water. SWOT observes the fine details of the ocean's surface topography and measures how water bodies change over time.

SWOT carries seven instruments. Its primary instrument is the Ka-band Radar Interferometer (KaRIn), used to measure water surface heights on land and in the ocean. It also carries a Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) receiver, which is used for precise orbit determination.

SWOT's instruments provide detailed information about sea level changes and are used to detect ocean features such as eddies, fronts and waves. This information can improve ocean models and forecasts. SWOT also measures surface water level changes, providing more detailed measurements of river and lake volume. These records provide historical data about flooding and drought, which could be used to improve forecasts.