Mosanna
Petra follows the directions given her- keep to the road going west from Lucimburic, which eventually reaches the Chier river, which flows to the Meuse. But Hermod seems to know where he's going anyway. By now, Petra has accepted that Hermod's directional accuracy is a natural gift. Unicorns can heal, but Winged Horses know where they must go, it's as simple as that.
The Meuse River is one of those rivers that manages to surround itself with extraordinary scenery. It winds and twists among green hills, sometimes turning around so sharply that it almost forms a complete loop. Facing the river, the hills are sometimes covered in a blanket of forest, but sometimes show dramatic exposed rock face. From above, the land appears to be mostly wilderness. But following the river Petra finds villages, scattered like lonely beads on a watery necklace.
The only question is... where to find a River Goddess? From what she knows such beings are the spirits of the rivers they inhabit. Where the river is, they are. Which means, Mosanna is already here. But on the other hand, Petra knows that some places are more important than others, and are the places one must seek out if one wishes to make contact.
Hermod knows where. After a long trip following the river, Hermod singles out a rocky bank beneath a steep bluff. There is no sign of civilization at all, here. The trail that follows the river has diverted to the east, following easier landscape, so this particular stretch is completely pristine. Not even a felled tree.
(Right about in this place, the real world Meuse river flows along a place called Bois De Freyr- the Wood Of Frey. )