Ulmo and the Ring War

[Legate of Amon Lanc]

Originally Posted by Gordis

I think the last answer is the right one: Nazgul felt the lingering traces of Ulmo's power in flowing water and feared it.

Note that the Witch-King didn't fear water: Now, why didn't the WK fear water?

He was undoubtedly a powerful sorceror, a witch, so, if the reason were simply that "witches can't cross water" as in old tales, then he would be more affected than the others, not less so.

It is unlikely that the WK wouldn't feel as much "aversion to something so inherently clean and pure" as his fellows did.

So - we are left with Ulmo's powers. The WK was clearly the most powerful of the Nine, and the power of Ulmo was almost gone from the waters of ME. The Witch-King was simply powerful enough to disregard what was left of old Ulmo to enjoy swimming

I think this was not necessarily about that his power would be powerful enough to overcome the "traces of Ulmo". I think this was merely a kind of psychological effect, so to say. You say it yourself: He was not afraid of water. Whether the water did have any effect on him is a completely different question (and in the end, it indeed had... ). He may still have felt a little dizzy or uncomfortable in the water, like somebody who has an allergy or something, but he was not afraid - for what reason in particular, we don't know. He may have been simply more rational person than the others ("Other people and even Orcs usually go into the water and nothing happens. The chance is 1:500000 that something happens. I'm going to be a little dizzy, but as soon as this is over, I will lie down for a few hours and then I'll be fit again. It has been proven that the effects of hydronausea pass in 3-5 days completely, and that it is not hazardous even after long exposure."), or he may simply have had more self-confidence ("The water's not gonna stop me in my unholy quest! Forwaaards!").