For you Horde Druids out there, ignore all the above information about Darkshore and Westfall. If you speak the the flightmasters you'll get information on two places: North Tides Run (the north beach in Silverpine) and the Sludge Fen (in the northeast corner of the Barrens).
Sludge Fen is easy enough to find, just kill a few guys until you can get in the water safely. You'll find the chest towards the middle of the mucky pond.
The one out at sea takes a bit longer. Hopefully you have the Sepulcher as a flight path, because that will cut down on time significantly. North of The Sepulcher is a beach with a large wreck on it. Head straight west from the wreck on the beach until you hit the drop-off (right about when you hit the "Great Sea" zone). Down at the bottom is a fissure where you can breathe, next to the fissure is the chest. My coordinates showed 29,29 (titan panel) and I was in the Great Sea zone.
Sludge Fen is easy enough to find, just kill a few guys until you can get in the water safely. You'll find the chest towards the middle of the mucky pond.
The one out at sea takes a bit longer. Hopefully you have the Sepulcher as a flight path, because that will cut down on time significantly. North of The Sepulcher is a beach with a large wreck on it. Head straight west from the wreck on the beach until you hit the drop-off (right about when you hit the "Great Sea" zone). Down at the bottom is a fissure where you can breathe, next to the fissure is the chest. My coordinates showed 29,29 (titan panel) and I was in the Great Sea zone.