If you are interested in taking a boat out in South Tampa and you do not own one yourself, do not worry, you have options. From Riverwalk in Downtown you can rent a mini powerboat from the Riverwalk Boating Company or for a Group you can rent one of the Eboats. At the Convention Center you can also find rentals for kayaks, water bikes, and SUP's.
There are also a couple of taxi/tour boats located Downtown. There is the Tampa Water Taxi Company, The Tampa Bay Funboat and the Pirate Water Taxi. These trips will give you a new perspective on the Downtown area. I recommend going for one late in the afternoon so that you can check out the lighting near the waterfront. You can also go for a dinner cruise on the Yacht Starship.