POST /v1/tides
Returns tide predictions for a NOAA CO-OPS station: every high and low water in the window with its time and height above datum, the range between them, and which extreme comes next with the time remaining. Where the station also measures, the observed water level is fetched and compared with the prediction — wind and air pressure routinely push the real level away from the astronomical forecast, and that residual is the figure that matters for anyone near a limit, so it is returned rather than left implicit. A coordinate is resolved to the nearest station and the distance is reported, because a station 80 km away describes a different piece of coast. Coverage is United States coasts and territories only: NOAA does not measure the North Sea, the Baltic or the Mediterranean, and for a coordinate outside coverage the answer says so instead of returning a distant station as if it fitted.