Kelp Forest is the first zone in the undersea region known as Vashj'ir. It is one of the two starting zone for all players level 80 and higher (the other is Mount Hyjal). The forest features a vast array of aquatic life and plants.

There is a mixed focus between the main quests involving the naga and auxiliary quests introducing players to Vashj'ir's new under water mechanics. The most noticeable feature of the Kelp Forest is found along the southern edge of the zone in what is simply called The Abyss.

Kelp Forest [HD] - World of Warcraft Cataclysm

Video note:  Here is some underwater footage from the Sunken City of Vashj'ir. This entirely underwater zone is composed of three smaller maps: Kelp Forest, Abyssal Depths, and the Shimmering Expanse.

Cataclysm Kelp Forest Zone Review