tide gauge

An instrument that allows sea level variations to be measured and recorded, both near the coast and on the open sea. Commonly, the buoys on which tide gauges are installed include sensors that measure variables such as atmospheric pressure, air temperature, or wind, which turns them into meteorological or weather buoys. There are different networks of them, some of which (such as the Argo network) have global coverage, allowing the oceans as a whole to be monitored.