My niece and I will be in Dubrovnik at the end of May and plan to take the ferry to Split on 5/28. We would also like to spend a day on Mljet. Is it possible to to get off the ferry, spend the day and then catch a later ferry to Split or would we have to buy separate tickets for the two trips? Also, is there a place on Mljet to store luggage for the day? I can't find any recent updates about luggage storage. Thanks!
There is a catamaran that connects Dubrovnik to Mljet and then further to Split. Here is an article about the catamaran and ferry connections between Dubrovnik and Split https://www.tourdesksplit.com/dubrovnik-to-split-ferry-and-catamaran-guide/
In this article you will find ferry and catamaran schedule from Dubrovnik to Split.
On the 28th of May there is a catamaran that leaves Dubrovnik only at 4:00pm. You will land in Sobra https://www.google.com/maps/place/Sobraemail@example.com,17.5802188,14z/data=!3m1!4b1!4m5!3m4!1s0x134bbf6832a9291f:0x2600ad515335f692!8m2!3d42.7366918!4d17.5996568 (village on Mljet island at 4:50pm). However, you would need to buy 2 separate tickets since you would not be able to continue your voyage to Split on the same day. No info on the luggage though. I guess you would need to stay overnight on Mljet.