Go fishing#23 of 25 things to do in Dubrovnik
If you want to go to sea alone, then you will need a fishing permit, which can be purchased in any travel agency. In the main port of the city you can rent a boat or a yacht and start your journey.
The easiest way is to go to the port of Gruž, where you can find fishermen and ask one of them to take you with them. In this case, you do not need permission, and you can use fisherman's fishing gear.