Mljet National Park: the complete day trip guide from Dubrovnik

One of Croatia’s most beautiful national parks, reachable as a day trip

Mljet is a long, forested island in the southern Adriatic, about 50 kilometres north-west of Dubrovnik. Its western third is a national park — one of the oldest in Croatia, established in 1960 — protecting two interconnected salt lakes, dense Aleppo pine and holm oak forest, and the 12th-century Benedictine monastery on St Mary’s Island (Sv. Marija) in the larger lake.

The national park experience is defined by these lakes. Veliko jezero (Large Lake) and Malo jezero (Small Lake) are salt-water bodies connected to the sea by a narrow channel. They are calm, enclosed, crystal clear, and surrounded by nothing but forest and a walking/cycling track. You can swim in them, cycle around them, and take a small boat from the shore to the monastery island. On a calm summer day it is one of the more extraordinary natural settings in the Mediterranean.

Getting to Mljet from Dubrovnik

By catamaran: The Krilo catamaran (Kapetan Luka) and the Nona Ana catamaran (G&V Line) both operate services from Gruž Port in Dubrovnik to Polače, the village at the western entrance of the national park. Journey time is approximately 1.5–2 hours. This is the most practical option for a day trip — Polače puts you immediately at the park entrance.

By car ferry: A Jadrolinija car ferry operates from Prapatno on the Pelješac Peninsula to Sobra on the eastern side of Mljet. Sobra is about 25 kilometres from the national park entrance — not practical for a day trip without a car.

By guided tour: Several Dubrovnik operators offer full-day tours to Mljet that include catamaran transport, national park entry, and a guide. These are the most logistically convenient option.

Book catamaran seats in advance for July and August — the Krilo and Nona Ana boats have limited capacity and sell out.

Full-day Mljet National Park tour from Dubrovnik with catamaran and park entry

The salt lakes: Malo and Veliko jezero

The two lakes are the centrepiece of the national park. Malo jezero (Small Lake) is on the north-west side, Veliko jezero (Large Lake) to the south. They are connected to each other and to the sea. The sea connection means they are salt water — clear, slightly warmer than the open Adriatic, and home to marine species including eels, which have an almost mythological status in the lake ecosystem.

Both lakes are suitable for swimming. The water is calm (no significant waves reach the lakes from the open sea) and the depth is manageable. The most popular swimming spots are on the north shore of Malo jezero, where the path from Polače runs close to the water, and in Malo jezero’s narrow channel connecting to the sea.

The connection channel between Malo jezero and the sea has a strong tidal current at certain times — locals call it the “washing machine.” Do not swim here unless you are a very confident swimmer.

St Mary’s Island monastery

The 12th-century Benedictine monastery on an island in Veliko jezero is the most photogenic element of the national park. The small boat crossing from the shore takes about 5 minutes. The monastery complex includes the church of Sv. Marija (partially restored), a cloister, and the former monks’ cells, which now house a small restaurant and café.

Visiting the monastery is included in the national park ticket. The restaurant on the island is known for fresh fish, grilled meat, and the calm of eating surrounded by lake water on all sides. It can be busy at lunch — the boat journey back requires coordination with the departure schedule.

The monastery was active from the 12th century until the Austro-Hungarian period. The current building incorporates elements from several centuries of construction and modification.

Mljet cycling, boat, and beach day: lakes, monastery, and swimming

Cycling around the lakes

Bicycles can be hired in Polače or at Pristanište on the south shore of Veliko jezero. The cycling track around the larger lake is approximately 9 kilometres and takes about 45–60 minutes at a comfortable pace. The route passes through forest, along the lake shore, and through the village of Babino Polje.

The cycling is flat to gently rolling — the national park terrain is not technically challenging. It is a genuinely enjoyable way to see the lake perimeter and provides access to swimming spots that are less busy than those near the main boat dock.

A bike-plus-monastery combination is the most popular way to spend a full day in the park: cycle around the lake in the morning, take the boat to the monastery for lunch, swim in the afternoon.

Odysseus Cave (Špilja Odiseja)

On the south coast of Mljet, about 5 kilometres east of Polače, is a sea cave that local tradition associates with Homer’s Odyssey — the legend being that Odysseus was detained here by the nymph Calypso for seven years. The connection to Homer is not historically verifiable, but the cave itself is impressive: a large sea-level grotto open to the sky at the top, with deep blue-green water visible from the entrance and a swimming pool-like interior accessible by ladder.

Getting to Odysseus Cave from the national park lakes requires a short drive, boat trip, or significant walk (5 kilometres of coastal path). Several day-trip operators include it as part of a Mljet tour.

Mljet day trip from Dubrovnik with national park and Odysseus Cave

Practical information for visiting Mljet National Park

National park entry fee: Approximately €20–25 per adult in peak season; children under 7 free. The fee includes the small boat to St Mary’s Island.

Best time to visit: June and September. July and August are busy, particularly around the monastery island and the main swimming spots. The lakes are warm enough to swim from May to October.

What to bring: Swimming gear, water, sun protection, and cash (the park accepts cards but smaller vendors may prefer cash). Cycling shoes are not necessary.

Time needed: Minimum 5–6 hours in the park. A full day (departing Dubrovnik early and returning late) is more relaxed and allows for cycling, swimming, and the monastery.

Getting from Polače ferry dock to the lakes: Polače is immediately adjacent to the park entrance. The walk to the start of the lakes circuit is about 10 minutes from the ferry dock.

Combining Mljet with Korčula or Pelješac

Mljet is at the midpoint of a broader South Dalmatia itinerary that includes Korčula and the Pelješac Peninsula. The Korčula, Mljet, and Pelješac loop itinerary covers how to combine these three destinations over several days without a car.

For the broader island context, see best islands near Dubrovnik and best day trips from Dubrovnik.

Frequently asked questions about Mljet National Park

Is Mljet National Park suitable for children?

Yes. The lake swimming is calm and safe. Cycling is easy. The monastery island is interesting for older children. The main consideration is the journey length — 1.5–2 hours each way on the catamaran is long for very young children.

Can I stay overnight on Mljet?

Yes. Polače and the surrounding villages have a few small guesthouses and rental apartments. The village of Babino Polje on the south side of the island has more options. Staying overnight lets you have the lakes to yourself in the early morning.

Is Mljet National Park worth it compared to the Elaphiti Islands?

They are very different experiences. Mljet is a full day, primarily about nature (the lakes, cycling, monastery). The Elaphiti are closer, more populated, and better for a relaxed beach day or short island hop. Mljet is the more dramatic destination; the Elaphiti are more convenient.

Are there cafes or restaurants in the national park?

The restaurant on St Mary’s Island (monastery) is the main option inside the park. Polače village has a couple of cafes. Bring food if you want to eat lunch away from the monastery.

How far in advance should I book catamaran tickets to Mljet?

In July and August, book Krilo or Nona Ana catamaran tickets at least 1–2 weeks in advance. Both boats fill up. In June and September, booking 3–5 days ahead is usually sufficient.

What is the best route if I only have one day in Mljet?

Polače → small boat to St Mary’s Island monastery (morning) → swim in Malo jezero → cycle around Veliko jezero → swim again → return catamaran to Dubrovnik. This covers the park’s highlights in 6–7 hours on the island.