Sargassum (population 9,000 adults) is located 420 miles southeast of the oyster reef opening, in an area of thick seaweed amidst new and ancient wrecked ships. On the surface of the dense seaweed patches live swarms of monstrous aquatic termites – the real cause of the wrecks. As a ship enters the 15,000 sq. mile doldrums of choked water, the termites eat at the hull which invariably sinks the vessel. Rumors of hostile merfolk persist to explain the wreckages. Hundreds of imperiled sailors have been mysteriously saved by elves, although the disoriented sailors only remember distorted images of merfolk.

Underwater, Sargassum is like any sylvan elf community, existing deep within a forest. Just as any surface forest is full of animals and monsters, so too is the Seaweed Forest. Even moreso due to the large quantity of sunken ships and jetsam to hide in and behind. The empty hulls of great sunken sailing watercraft provide lairs amidst the massive seaweed stalks. The largest of these vessels lies just east of the Seaweed Forest. It is an enigmatic ship of mythical proportions, its length reaching nearly 3,000 feet long and hundreds of feet wide. No one goes near the craft, as hostile gargantuan stingrays protect the sunken vessel from approach. Those few that have seen the ship report that lights can be seen intermittently from portholes that surround the ship, and "shadows that move within."

It is known a thorp of lacathah inhabits the southernmost depths of the Seaweed Forest, as well as a several dozen highly dispersed families of merfolk and tritons. The hungry and carnivorous sea cats are a constant threat to inhabitants, as are an annoying race of marine pixies. Occasional forays into the forest by skum have been known. A recent plot to overthrow Sargassum was thwarted with the destruction of a kraken, controlled by the evil box jellyfish "Irukandji" (Fine sized) who escaped destruction. In a seemingly unrelated matter, a persistent sea demon has plagued the area for over a century, promoting evil creatures to move into the forest, such as a finned medusa, gilled harpies, and a family of lycanthropic stingrays.

Leader of Sargassum: Barqu of Sargassum, male aquatic elf Brd12/Clr7; AL LG; Survival +22; Leadership, Weapon Focus (trident); Animal companion "Quat" (Large animal, dire porpoise, HD 8d8+2, Spd 130 ft. swim, AC 16).