Day trip to Mljet from Dubrovnik

The ferry logistics

Fast catamarans (Krilo or G&V Line) leave Gruž port at 9am for Pomena or Sobra, taking 1 hour 45 minutes, €19 one way. Book the return in advance — usually 4:15pm from Pomena. The slower Jadrolinija car ferry takes 2 hours 20 minutes but costs €9 and lets you sit on deck. Bring a picnic; the one shop in Pomena is limited and closes at 3pm.

Book the fast catamaran online through Krilo or G&V Line at least three days ahead in July and August; the 9am departure is the only one that gets you into the national park by mid-morning, and it fills first. If you arrive into Sobra rather than Pomena, budget an extra 40 minutes and about €5 for a taxi or connecting bus across the island to the park entrance at Pristanište. The Jadrolinija car ferry also runs a slower route from Dubrovnik via Sobra most days, useful if you're bringing a rental car, but it adds an hour each way that a day-tripper can't really spare.

What to do in the national park

Park entry is €23 in July-August, €13 in shoulder season, and includes the boat to St Mary's island in the middle of Veliko Jezero. Rent a bike at Pomena (€7/day) and ride the 8 miles around the two lakes — flat, shaded, and one of the loveliest cycles in the Adriatic. Swim at any of the numbered points; the water in the lakes is warmer and clearer than the open sea. The 12th-century Benedictine monastery on St Mary's is 20 minutes on foot from the boat dock.

Beyond the lake circuit, the trail up Montokuc — at 253 metres the highest point on Mljet — starts near Veliko Jezero and takes about 90 minutes each way, with views over the whole park and, on a clear day, across to the Pelješac peninsula. There's a small café-bar with a terrace on the northern shore of Veliko Jezero where you can refill water bottles and get a coffee between swims; it's the only food stop inside the park boundary. Kayaks can be rented at the same spot for €10 an hour if you'd rather paddle the lake than cycle around it. Aim to be back at the bike-rental kiosk by 3:30pm to leave time to return it before your ferry.

Beyond the park

If you skip the lakes for a beach day, Saplunara on the far southeast of the island has one of the only true sand beaches in the region — but it's a 40-minute drive from Pomena so you need a rental scooter (€26). Odysseus Cave, reachable by kayak from Pomena in 1 hour, is a swim-through sea cave with a shaft of sunlight at midday. Neither works easily if you're on a day trip; consider staying overnight.

Polače, on the northern coast, is worth a look even from the ferry deck — the harbour is ringed by the ruins of a 5th-century Roman palace, one of the largest Roman structures on the Adriatic coast, and a short walk from where the Jadrolinija ferry docks. Babino Polje, the island's largest settlement, sits inland and has little to detain a day-tripper beyond a couple of grocery shops and a bakery. If you do stay overnight to reach Saplunara or Odysseus Cave properly, base yourself in Pomena or Sobra rather than Babino Polje — both have small guesthouses within walking distance of the harbour, whereas Babino Polje leaves you needing a scooter for everything.

Where to eat on Mljet

Pomena's harbour has three or four konobas serving grilled fish by the kilo and the island's own lamb, janjetina, roasted under a bell (peka) if you order it a few hours ahead. Expect €18-€28 for a main and €20-€25 for a bottle of decent Pošip from the Pelješac peninsula across the channel. The restaurants directly on the quay where the catamaran docks charge a couple of euros more for the same dishes than the ones a two-minute walk further round the bay — worth the short walk. Skip the pre-packaged sandwiches sold at the ferry kiosk; the bakery in Pomena, open until 1pm, does better bread and pastries for a fraction of the price.

Best time of year to visit

June and September give the best balance: the lakes are warm enough to swim (low-to-mid 20s Celsius) but the July-August entry fee of €23 and packed 9am catamaran are avoided. October through April the national park itself never closes, but the boat shuttle to St Mary's island runs on a reduced, weather-dependent schedule, and Pomena's few restaurants and the bike-rental kiosk shut down for winter entirely, so a self-guided walk around the lakeshore becomes the only option. Winter entry is free. If you can only travel in August, take the earliest possible catamaran and rent your bike within the first half hour — by 11am the loop around Veliko Jezero is far busier and the bike stand can run out of bikes.

Combining Mljet with other islands

The same catamaran that calls at Mljet in summer continues on to Korčula Town, about 50 minutes further, and some sailings carry on to Hvar and Split. It's tempting to try to bolt Korčula onto a Mljet day trip, but the timetable doesn't support it there and back in a single day from Dubrovnik — you'd need to either stay overnight on Korčula or skip Mljet's national park almost entirely. If island-hopping is the goal, treat Mljet and Korčula as a two-day trip: one full day for the lakes and bike loop, a second for Korčula's old town and the Marco Polo house, sleeping over on either island rather than commuting back to Dubrovnik in between.