The River Vid stretches through approximately 20 map tiles in a C-shape around the perimeter of the world map, from Slaeter's Sea in the southeast, to Bifrost in the southwest, around to Mimer's Realm in the northeast. The River Vid is also adjacent to the Outer Sea which contains nothing but water and the evil serpent god Jormungand.
The most natural access point is Slaeter's Sea, but one can teleport to a random part of the river by dimension traveling to dark blue.
No artifacts or special loot can be found in the River Vid, but it does contain enough random treasure to be worth exploring, for a mid-level player that isn't comfortable with tackling a main quest.