Mahon Harbour Boat Tour with Underwater Viewing

Mahón harbour, Menorca's natural port

Mahón, or Maó in Catalan, has been the capital of Menorca since the 18th century, and its harbour is the reason. The port is a deep, narrow inlet about five kilometres long, sheltered by high banks on both sides, and it is one of the largest natural harbours in the world. For centuries navies fought to control it, which is why its shores are lined with forts, towers and military buildings.

The town of Mahón sits on a cliff above the water, and steps and winding roads lead down to the quays, now lined with restaurants and boats. The famous mayonnaise sauce is said to take its name from the town. To get to the Moll de Llevant quay, walk down from the centre in about 10 minutes, or drive and park along the waterfront.

King's Island and its old hospital

In the middle of the harbour lies Illa del Rei, King's Island, a small island where, according to tradition, the medieval conquerors of Menorca first landed. In the early 18th century a military hospital was built here, and its long buildings with arched galleries cared for sailors and soldiers for two centuries, earning the island the local nickname Hospital Island.

After decades of neglect, volunteers restored the hospital, which now houses a small museum, and the island has become a cultural space with gardens and exhibitions. From the catamaran you see its pink-and-ochre buildings reflected in the calm water. Your guide explains its history as you pass, and many travellers later return by water taxi to visit.

Quarantine Island and the Lazaretto

Further along the harbour lie two islands linked to the history of disease and trade. Illa de la Quarantena, Quarantine Island, was where ships arriving with suspected infections had to wait before entering the port. Next to it, on a peninsula turned into an island by a canal, stands the Lazaretto, a huge walled hospital built between 1793 and 1817 to isolate travellers during epidemics.

The Lazaretto is one of the best-preserved quarantine hospitals in Europe, with high stone walls, separate courtyards for different levels of risk and a chapel designed so that patients could follow services without touching each other. Seen from the water, its massive walls tell the story of how Mahón protected itself while remaining open to Mediterranean trade.

La Mola fortress and the harbour mouth

At the entrance of the harbour, on the northern peninsula of La Mola, rises a vast 19th-century fortress, one of the largest military buildings in Europe from that era. It was built to make the port impregnable, with bastions, gun batteries and tunnels dug into the rock. Today it is a museum, and its walls stretch along the clifftops above the open sea.

The catamaran sails towards the harbour mouth so you can see the scale of the fortress and the change from the calm inlet to the deep blue Mediterranean. Is a Mahón harbour boat tour worth it? For history lovers, this is the best way to understand how the port shaped Menorca, and it takes just one hour.

Es Castell, Cales Fonts and the underwater world

On the southern shore lies Es Castell, a village of neat sash-windowed houses built during the British period in the 18th century, with a parade ground and the little harbour of Cales Fonts, where old fishermen's caves are now waterfront terraces. It is the most easterly town in Spain, so it sees the country's first sunrise.

Throughout the trip you can go down to the underwater viewing cabin, where large windows below the waterline show the sea grass, rocks and fish of the harbour: bream, mullet, wrasse and sometimes octopus. Children love this part. The best time to visit Mahón harbour is from May to October, and the morning departures usually offer the calmest water and clearest views.