@Guillaume I should have specified, I'm on Xbox, so I won't be able to use console commands. I used the "Xbox record that" functionality, but I did it after I had fallen in. The subsequent video is listed here. I do remember falling "behind" the leg of the bridge between the hill and the wall, when I hit the water. I'm wondering if this affected how the water was to appear and didn't work? I wasn't far in the game at all, so I don't mind beginning again. Thanks for your response, I appreciate it.
I was walking around the garden area having just made it out of my safehouse area. I incapacitated the runner and picked up his body to throw it in what I thought was a river by the bridge you take to go to Holm's. However, I got too close to the "river" and happened to fall in with the runner's body. I expected to die, but it appeared to just be a ravine. I ran around in the ravine looking for a less steep incline so that I could get out and continue, but I eventually just found a vast expanse of open area and the sounds changed to what seemed like waves lapping up on the shore of a beach, but no water was found. Is this a bug, or did I just not follow the walls around to find a set of stairs or a less steep hill?