Tanaris is Calling (Horde)

There is actually a little 'cul-de-sac' at coords 74.95...take your boat from the speedbarge there and there's an uphill path that takes you right into Tanaris.

Orrrrrrrrr.....you can sail south of Speedbarge.

reference: threadmeters . com/v-1but/How_do_you_get_to_Tanaris_now_horde [new comers can't share links unfortunately hence the spacing between the period above]

"Well the whole point is that you can easily get to Tanaris if you level in Kalimdor. The quest line sends you to the Speedbarge where you have quests to give you a river boat. Short of that you can swim which would take a couple minutes of your life and you just swim to where the old path from Shimmering Flats went into Tanaris. It's not like the zones completely were shifted and mangled, Thousand Needles is exactly like it was when you left it, just now under a couple hundred feet of water. " ~Cloaknpoke

The text in bold is pertinent ;] Especially if you do not use coordinates [I prefer my map, to each their own].

No troubles if you cannot fly. Look for the small bump in the middle of the curve at the bottom of your map - that is the beginning of the path through the hills. There is also a road still on the lake bottom that runs north to south on the west side of the barge. Just follow that south and you will be in Tanaris in no time.