Discover Barcelona with your own transport, and rent some wheels. There are now countless places where you can rent a bike, especially in the more central districts of the Born, Gothic and Barceloneta. For those who prefer to move faster and with less effort another option would be an electric bike which gives you the option to switch from pedal power to battery. This might make scaling the heights of Montjuïc a more appealing prospect. Or, you can really go easy on the legs and rent a scooter or Vespa. These are easy to park and allow maximum flexibility for you to discover Barcelona at your own pace, whilst following your own interests and instincts. Almost if not all of these bike and scooter rental companies also offer bike tours or scooter tours, where you can relax and leave the route navigation to someone else whilst you enjoy the sights and absorb the snippets of local knowledge and insights they will be showering you with.
You´ll find all the standard car rental companies at the airport and train station, as well as other locations throughout town.
As for boat rental, yes this is a Mediterranean city, and yes if you have a skipper´s licence you can cruise it cool on the waves for a day. Boat tours, or hiring a skippered boat might be a more feasible option for most of us, and there is plenty available.
Find Tours Information here.