The Stygian Bounty is a Hordeship floating on the surface above the Shimmering Expanse in Vashj'ir. It is one of three Horde ships in the area searching for survivors of the ships that are wrecked at the start of the Vashj'ir storyline.
Arriving on the ship triggers the "discovered message", but the subzone name on the minimap doesn't change to this.
It is from here that Horde players progress through Vashj'ir by boarding the Horde submarine The Verne, the players are then taken to the Abyssal Depths.
To get onto the ship from the water click the rope ladders that appear on either side.