If you come out of the front door of the Harman and turn left, you walk up directly towards the market - if you come out and follow the road down in the other direction you quickly come to the aquapark dual carriageway road. Cross that and either turn right to the (Dolphin) roundabout, turn left there down to the water taxi. Or cross the dual carriageway and don't turn right, go straight on, turn right and cut through to the water taxi from the other direction.
10 minutes max for either (market or water taxi).