Quote Originally Posted by Iscah View Post
Halatali is an optional level 20 dungeon. The quest starts at Vesper Bay, probably intended that you pick it up when first inducted into the Scions.

Generally speaking, make sure you pick up sidequests with the blue "plus" symbol because they always unlock something - either optional dungeons or extra game features.
Just to add to this: The quest is called "Hallo Halatali" and is given to you by an NPC named Nedrick Ironheart - hes located at x12, y14 in Vesper bay in Western Thanalan.