Information for this sticky:
To take the Sapphire Falls water taxi from CBBR, walk out the main lobby of CBBR and head for the traffic light at the road. Go straight across the street to SF property and head for the main lobby entrance. Say 'hi' to the bellhops as you enter. Notice the unique chandelier above you.
Toward the back right of the lobby is a curving stone wall. In there is a spiral staircase that you take down to the bottom. Walk straight out, past the restaurant on your left and through the doors. You are already on the walking path to the boat dock below.
It takes about 5 minutes to walk. Your wait for boat will vary. Given that you get disembarked well within City Walk, you will have saved many steps. The amount of time for the trip overall to the actual entrance of the parks is about the same as taking the CBBR bus.