The ferry connections between Hvar and Mljet are very limited. In fact, there is only a catamaran connection in the summer months between Hvar town and Pomena on Mljet. The catamaran line operated by Krilo – Kapetan Luka sails parts of May, daily in June, July, August, September, and parts of October. The catamaran leaves Hvar early in the morning and arrives in Pomena before noon, sailing time is around 2 hours.
Hvar town Pomena , 2022-11-27
28.04. - 15.10.
Map travel route Hvar town - Pomena
Alternative ways of traveling, hmmm that is a tough question! The only options I can think of are to take the catamaran from Hvar to Korcula town and then catch the 10:30 departure from Korcula to Sobra on Mljet, other alternatives would require going to either Dubrovnik or Prapratno on Peljesac.