I made a how-to video on reaching various "Aquariums"... the columns of water that now extend far below Azeroth's surface.
*EDIT: All of these "Aquarium" spots can now be used to fly underneath the continents. Simply mount up instead of jumping and fly underneath!
In this first video, I explore aquariums in Tanaris, Felwood, and Dun Morogh (including the IF Airport Aquarium).
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In the second video, I explore aquariums in Booty Bay, Stonetalon Mountains, and Stormwind (both the Sea and Crystal Lake). All video was taken on a live server during patch 4.0.3.
(credit to Omo of RAoV for first discovering the Durotar 'aquarium'!)
((LONG LIVE THE FISHING CHAIR))