Your Garmin GPSMap66SR does have a Barometric Altimeter that needs calibrating on a regular basis to keep the height data from elevation accurate, we also recommend that you always reset the the Altimeter data before each activity as follows:


Calibrating Altimeter:

From the Altimeter page - press your menu button once - select Altimeter Setup

Scroll down and Select Calibrate Altimeter

If you know your current height scroll down to the box under Method that displays height data - press Enter - type in your know height and then move the cursor to Done and Press Enter - Then move down to the word calibrate and Press Enter


You  can also select Method - Press Enter

You can now select to calibrate from Current Elevation if the device was displaying this correctly or if you know barometric pressure select from Sea Level Pressure or finally if you are happy with your GPS Elevation reading from Satellites Select GPS Altitude (You must have a full Satellite lock to Calibrate from GPS)


Resetting Altimeter / Trip Data before an Activity

From the Altimeter page - press your menu button once - select Reset
Select the first option Reset Trip Data and press Enter - Select Reset to confirm and press Enter

Then Select third option Clear Current Activity and Press Enter - Select Reset to confirm and press Enter


We have videos on our Online training resource for paid members under Courses - Garmin Units - GPSMap66 - Module 3 - that show you the above calibration methods - More info here 


When recording an activity if you are seeing higher Ascent and Descent figures than expected, there is a possible calculation error that Garmin are working on, this does not affect the current height displayed just the total Ascent & Descent figures at the end of an Activity that are displayed.

If you do experience this problem please email Garmin directly to - helpdesk.outdoor@garmin.com
Quote the following text  - Ref: PSC-384328 - Helpdesk team is aware of this



We have many more tips and training videos to get you going with your Garmin Handheld GPS device and Garmin's Basecamp planning software on our Online Training Resource - More info here

Buy and learn from the experts - GPS Training