SonTek, founded in 1992 and advancing environmental science in over 100 countries, manufactures affordable, reliable acoustic Doppler instrumentation for water velocity measurement in oceans, rivers, lakes, harbors, estuaries, and laboratories. SonTek is headquartered in San Diego, California, and is a division of YSI Inc., a Xylem company that provides monitoring and data collection instrumentation to global water quality, water quantity, and aquaculture markets. Simply put, our instruments use sound waves to tell you how fast water is moving, where it is moving, and even if it is not moving at all. Our customers are scientists, engineers, hydrologists, research associates, water resource planners and anyone that needs to collect velocity (speed) data in every kind of body of water imaginable. SonTek solutions improve the measurement of water movement and associated parameters in coastal and inland areas by: (1) simplifying operations to reduce time and labor costs, (2) employing advanced technologies that provide consistent and continuous high-quality results, and (3) enhancing capabilities to enable data collection in areas previously thought immeasurable. Our products could be as easily found in a university laboratory as they could in the deep ocean, along the coast, or in a river, lake, or stream. From the depths of the Pacific Ocean, to the Amazon River, to the small creek in your backyard, there are SonTek/YSI instruments hard at work every day.