GPS altitude incorrect

I realize the barometric altimeter is only going to be useful for a short period of time after calibration since the weather is going to change.

However, when I go down to the ocean and select settings/watch sensors/barometer and calibrate using GPS, it shows that I'm currently 65 feet above sea level. But I'm probably only about 15 feet above sea level.

Is this expected behavior, ie. is this "accurate enough"?

0 Garmin-Sara over 1 year ago

Elevation calibrated by GPS is accurate to +/-400 feet at any given point with a strong GPS signal. Elevation is determined by the device acquiring a GPS signal, while maps will provide elevation information based on survey data. GPS elevation readings may be different than elevations on maps or marked on trails and roads.

For more information you can review Elevation Accuracy of Outdoor and Fitness Devices or if you have additional questions please feel free to reach out to Product Support for assistance.