when you go for walk around town, and especially the harbour, you get approached by men trying to seel you all kind of trips. Dont fall for it as you cant be sure the trip exists, and you will end up losing money.
One day I was waiting at the harbour for some guests to come on with the taxiboat I was talking to some other guests there. we were approached by a man trying to sell us all kind of stuff. He talked a lot about a nightclub with male strip. he was talking about free drinks for the women who got there before midnight , and we talked a bit about stripping. The the husband of the danish guest showed up and the male excused himself for talking about male stripping to a married woman. then he went off! poor fella!
In case you wont to rent local type of rowing boat, you better check its conditiones before. If there is a long period of sunny and dry weather and you find the bottom of the boat is wet just quit of renting it.
In case you don't trust to my advice, this is what might happen to you. You might be happy if this happens when still in the harbour, don't even try to imagine what could be if in open sea.
Watch for those 'friendly' guys in the old town on riva. They might seem like they are trying to help you, but they are usually selling excursions or exchanging currency, but you can find better deals at a legal place.