I am very very skeptical of the elevation data I get from Garmin Etrex Legend. I can at 20 feet or better accuracy and watch the elevation reading scroll up 20 feet, down 15 feet, down 8 more feet and then back up 17 feet, all in the course of a few minutes. I think the hand held GPS units handle X and Y coordinates (lat and long) much better then Z (elevation). It may be due to satelite position, but I have rarely gotten elevation data that I trust from my GPS.