One of the most popular day trips from Dubrovnik is the Elafiti Islands. It is possible to reach them on your own by local ferry boat, but it is difficult to see more than one per day that way. A great way to see all three in one day is the Three Island Tour. The tour leaves from various locations including Gruz Port, Old Town, Lapad, Zupa, Plat, and Cavtat. Aboard an old wooden boat, you will visit the islands of Kolocep; known for its bountiful fruit orchids; Lopud, known for its beautiful sandy beach; and Sipan, famous for its aristocratic history. Tours include a lunch of fish and white wine and entertainment by local musicians. Prices vary by tour operator, but are generally between 40 and 50 Euros per person. It is said that Dubrovnik is best seen from the sea, and this is a great way to explore the area in a short time. Be sure to bring a bathing suit as there are lots of opportunities for swimming along the way.
Tours can generally be booked a day in advance by walking down to the port from which you plan to depart.