There's a small patch of water poking through the ground on the Barren's side of Southfury River. Nearby this patch is a very small area where you're able to drown on land, as shown in the second image.

To reproduce this, you simply need to cross the Southfury River and look behind the cluster of trees across from a zeppelin tower, there you'll see the patch of water described above. The exact location is shown in the first image.

That patch of water I don't believe is supposed to be there, and the small area right next to it where you can drown on land is definitely not supposed to be there.

This occured to Tripletung on the N'Zoth realm at 12:16 AM Mountain Standard Time, but I imagine this bug occurs on all realms.