Depends on your point of reference though; the lowest lying lowland is around 3600m "tall" when measured from average ocean floor depth rather than sea level, a

Depends on your point of reference though; the lowest lying lowland is around 3600m "tall" when measured from average ocean floor depth rather than sea level, and a 2500m seamount might be sitting in a valley surrounded by the underwater edges of continental shelf that's at least twice as high as it. By our usual standards, they're -1000m tall :)