It's a mixture of actual water... created in a constructed river, and CGI. But again... it's not so much the CGI as it is the action sequence. I'm sure that were I too focus on the CGI itself it would not appear as remarkable to me.... but that's my point. It doesn't get in the way of the action. I can only speak for myself, of course... but...
During the scene, (it's a very long sequence), I'm so focused on the action that the CGI is secondary in nature... it's a compliment to the scene and not the focus.
