I have the Dig 330M and it doesn't calc or display average depth. I also checked the specs and confirmed. That would be a nice feature for a more accurate SAC/RVM calc. I am missing something or do you have different model?
No Avg depth per the ScubaPro website:
A very practical instrument that incorporates state-of-the-art microchip technology, and several basic dive instruments into a compact information center. Depth rated to 1082 feet (330 meters).
* Includes precision digital depth gauge, dive time, and thermometer: displays actual and maximum depth (up to 1082ft), dive time and temperature (water and air).
* Automatic turn-on and off: it is automatically ready to dive after a self-test
* Surface interval displayed for 24 hours
* Logbook for the last nine dives
* Automatic altitude compensation
* Available as wrist unit
* Variable ascent rates in % and fast ascent warning; variable ascent rate warning (20-66ft/minute) for safer diving.
* Long battery life for over one thousand 1-hour dives.
* Temperature (water and air)
UWATEC DIGITAL DEPTH GAUGE - SCUBAPRO-UWATEC