Ysiel Windsinger wants you to look for signs of Cenarion Expedition Druids near the entrance to Coilfang Reservoir.
I sent a small group of our druids to investigate the drain you discovered inside of Serpent Lake. They were expected to return shortly after. Needless to say, they did not. You are amongst our most capable allies; I ask you to seek them and find out what became of them.
Thank Cenarius you showed up. My injuries prevented me from going back to the outside for help.
Upon completion of this quest you will gain:
You will have to swim "into" the drain in the middle of Serpent Lake. This will take you into Coilfang Reservior. In this chamber you will find Watcher Jhang sitting on the edge of the watter. (This is also the room for the entrances into the Underbog and Slave Pens instances)