Once you reach Svartalfheim in God of War Ragnarök, there will be 13 Odin's Ravens for you to claim for your potential rewards. Here's where to find the Raven located in The Watchtower.
Although there are 13 of the 48 you need to claim to complete the respective quest, some of the Ravens found in Svartalfheim will not be accessible until you complete additional main story quests or begin a specific sidequest. The Raven in The Watchtower, however, will be free for you to claim during your first visit to the area, and, like all others, can be returned if you miss it.
Where to Find Odin's Raven in The Watchtower
The Watchtower is an area that splits the Bay of Bounty almost directly in half. The Raven can be seen flying around the area during your boat ride through Svartalfheim. Once you've disembarked at The Watchtower, the Raven can be found to the left of Draugr Hole behind the actual watchtower. If you use your map, you can position yourself to face Nidavellir to get a better angle of the Raven.
Once there, there will be a gap in some of the trees overlooking the water. The Raven, which will be flying around, should eventually come into view. Unfortunately, you'll have to time your throw correctly to hit it, so you will need to allow yourself some time to study its flight path. The Raven here is the only one in The Watchtower, so once you've claimed it, you'll be free to move on to others.