The entrance to Veksar: The Invasion is through a mostly-buried door on the deep-water side of an underwater dome in the Lake of Ill Omen, located at 631,-182,289 . From where the river meets the lake, go out past the Yha-Lei platforms until you see a dome on the floor of the lake. There is a spire on top of the dome which sticks up just out of the water.
With GU48, we gained access to Veksar: The Invasion. This is an introduction, or teaser, to the full zone which is slated to be included with The Shadow Odyssey. It has a single item-triggered quest inside the zone and several outside quests (starting at Omen's Call), and is not terribly difficult. There is a door in the last room that will not open, presumably until the expansion launches in November.
Veksar was a Kunark zone in EverQuest, and is mentioned in the Living Legacy promotion as a group zone slated for GU48. The Allakhazam EverQuest site has this description of Veksar in the days of old:
VEKSAR: Shortly after the Shissar were run out of Kunark, a resort by the name of Veksar was built by the Kylong Iksar Tribe. After standing upon a lake in the middle of Kunark for nearly 1,000 years, Veksar was destroyed by the dragon Garudon, and sunk to the bottom of what is now known as the Lake of Ill Omen.
Now beneath the surface of the lake, Veksar is inhabited by sealife and the spirits of those killed in the incident. It is said that the spirit of the dragon Garudon also resides somewhere in the ruins. Only a few adventurers who have chosen to trespass in to Veksar's confines have been able to return to tell about it.