Hi!
When we were there in March, we pool hopped from RPH to HRH one afternoon aftering hearing so much about the HRH pool. We took the water taxi which stops at Citywalk and then you transfer to HRH. It worked out okay, and it was fun to see the other pool, but we weren't interested in doing it again. You can walk, but it is a long walk, so the water taxi is your best bet. Hope this helps!