* By Elevation: If we're talking about the lowest peak above sea level, then it's Mount Pico in Hawaii, rising just 1,800 feet above sea level. However, keep in mind that Mount Pico is actually a volcanic vent and not a mountain in the traditional sense.
* By Relative Height: If we're considering the height difference between a mountain's peak and its base, then the answer gets more complex. There are many hills and small rises that would fit the definition of a "mountain" based on relative height, but we don't have a comprehensive database of these features.
So, the answer really depends on how you define "mountain".
