We were keen to do this trip but the cost seemed high. We walked down to the lake from the Central Square and turned right, following the path along the side of the lake. Every 5 minutes or so we were approached by 'tour reps' trying to sell us boat trips through the Islets. We have read then some of these are unlicensed so had no intention of booking through them. Once we had arrived at the pontoons where the official boats depart from we faced another onslaught of tour reps. They are not in the least pushy and unlike other places in the world the chaps do take no for an answer. The price started at $30 each for a 2 hour trip (not sure whether this was a private tour or with others. We thought we'd return the following day as it might be quieter. The chap then offered us a 1 hour trip for $5 each. We accepted. We joined a group and returned 1.5 hours later having seen everything we planned to see. Suggest that if you are on a budget don't book in town but take a walk (or a cab - it's a long walk from the Central Square) and see if you can get a deal.