Broken barrel on west coast (near Watcher of the Fields) roughly ( 1399, -1, 153 ) /waypoint 1399, -1.42, 152.75.
Beware that some pirates will spawn when you approach. If you are careful or run you can kill them later for a quest update.
Shrine of the Sirens ( 1481, -20, 239 ) /waypoint 1481, -20.4, 239. This is a location update.
Pile of Bones in a Ship Wreck ( 1658, -58, 105 ) /waypoint 1658, -58, 105.
You have to go under the top deck, the bones are in the ships ribbing. This is very difficult without water breathing. You must be at least level 25 to click the bones. (Verified by a GM when the quest appeared bugged.)
Kill 4 pirates. If you followed the above information you will have less to find. The pirate camp in the gully in the previous quest (near ( 752, -20, 937 ) /waypoint 752, -20, 937) is the only known spawn point of pirates in the Steppes.
Return to Drinna and speak to her
You suddenly realize that she is one of the pirates, but she runs off before you can react!