The Swamp of Sorrows is a marshland in southern Eastern Kingdoms previously filled with green dragons serving Ysera (which could be farmed for the Tiny Emerald Whelpling). These days you can farm the whelps in Northern Feralas for the pet.

When the Dark Portal imploded during the Second War, The Black Morass was split in half – the northern part became the Swamp, while the southern half became the barren Blasted Lands. The Horde base of Stonard remains while the Alliance now have a town located on the lakeside near the Sunken Temple.

In addition, the coastline that once enclosed the Temple’s Pool of Tears is now open to the sea.

Lord Captain Wyrmak Swamp of Sorrows Rares

In Cataclysm, this rare is no longer a Lord and has been relocated inside Sunken Temple.
Chupacabros
Dreamwalker Forktongue

Fingat Swamp of Sorrows Rares

Gib the Banana-Hoarder
Gilmorian

IonisJade Swamp of Sorrows Rares

Kash

Lost One Chieftain Swamp of Sorrows Rares
Lost One Cook Swamp of Sorrows Rares
Molt Thorn Swamp of Sorrows Rares

Orlix the Swamplord
Seawing
Shimmerscale
Yukiko

Removed

Veyzhak the Cannibal