Bad barometric altimeter elevation data

Barometric uses atmospheric pressure data.

Elevation uses GPS / map height data.

You're comparing cheese and chalk.

I'm using GPS height data to show how wrong my barometric altimeter is. First run is off by - 70m under sea level at the end. Second run is off by +100 meters. Despite both runs being out and back courses, barometric altimeter data is also not symmetric.

If you had taken a second to a look at the post I linked you'd have read other users with the same problem. One of them obtained an exchange. 

Can you post links to the activities rather than screenshots and then we can have a better idea of the problem

That I'll do with Garmin Support since I keep my activities private. I wanted to bring awareness of a problem at least a few users have found. I thought Reddit was not the appropriate forum for the discussion. 

I'm having the same issue, see my post on this forum or my latest run. I must be an amphibian with all this underwater running.

Implemented barometric sensor has known limitation when used on the seashore. That's just how the things are. Sensor doesn't know that you are on the seashore, where conditions are very challenging with the zones of higher and lower air pressures.

Interesting, I hadn't read about this limitation. Thank you. 

There was a document on the old Fenix 3 board, but I can't find it right now.

Here is closest explanation: ci.coastal.edu/.../770Oceanatmosphere.htm

When air pressure changes - watch doesn't know if it is because you changed your altitude or it is because of change in weather, so watch tries to make decision. Also, when temperature start to change and your skin becomes hotter/colder, watch again has to decide what is going on.

I received a couple of storm alert notifications during my first run. I wonder if this is the reason.