Still talking this over but another question! Anduin has another ability (surprise!) called Mind Vision which allows him to see through the eyes of another. WoW has limited it to them being on the same Continent but for the sake of REALITY I'm saying that they're within sight of him. He also has the ability to Mind Vision hop from target to target across distances, so long as they are within sight of each other.

I was THINKING that maybe he could use this to hop across the mermaids/mist to be able to see closer who might be on the boats/how many there are?