The air pressure atop Mount McKinley is lower than is found at the same elevation on other high mountains in temperate latitudes. (sbnation.com)
And although the 17 are spread around the planet, they are at the same elevation plus or minus 177 meters (one standard deviation). (sciencemag.org)
Either because there's flow through the subsurface between the seas or because the channels between them allow enough liquid to pass through, the oceans on Titan are all at the same elevation. (sciencedaily.com)