I have not tried it, but would suspect immersion might result in some water ingress into the hub.
Two reasons for this, one is that Rohloff talk about the current hubs being built with 'labyrinth seals', which might imply they keep the oil in by virtue of their shape rather than by having heavy lumps of rubber which would cause extra drag.
The other is that the oil change instructions talk about removing the old oil and any penetrated moisture that might have found its way in. So Rohloff expect water in the hub to be fairly normal after 3100 miles.
My guess, based on gut feeling and no evidence at all, is that if you were to submerge your hub, it would be wise to carry out an oil change as soon as reasonably practicable afterwards. Just to be on the safe side. But I doubt it would lead to instant hub failure. Rohloff have made over 30,000 of them and report no failures. It might be reasonable to assume at least one of the 30,000 to date has been submerged in water.
As a student, I expect a more likely mishap would be for your Raven to be stolen or vandalised. I spend some of my working life in Essex University, and get to see the state of many of the bikes there.
