Enjoy sea kayaking#5 of 25 things to do in Dubrovnik
You should definitely reach a secret Betina Cave beach and stop there to dive from the cliffs. Also be sure to get to the Island of Lokrum - its beauty won't leave anyone indifferent. There are a lot of unusual spots for cliff diving here - you will have a great opportunity to chill out!
It's not a big deal to rent a kayak in Dubrovnik. You can rent it on Banje, Lapad or Copacabana beach, as well as on one among many sea kayak rent websites.