Even if you’ve earned the “Explore Tanaris Desert” achievement, you may not have really seen Land’s End Beach. Just for a point of reference it’s the spot on the map here with the big freaking arrow pointing toward it.
If you look south from this beach, you’ll see the shadowy outline of an island. Yesterday, I was doing the quest “Cuergo’s Gold” because someone put Cuergo’s Treasure Map in the guild bank. (ZOMFG, This Item Begins a Quest!) and I beheld the mysterious landmass. Figuring there was fatigue involved, I switched over to my priest so I could heal through it. After finding out that fatigue can be a bitch to manage, I made it into shallow water! So, in case you’re curious too, I have screenshots.
How low can you go? I think this is about it.