Turtle Island & Keri Caves Glass-Bottom Boat Tour Zakynthos

Agios Sostis Harbour

Agios Sostis is a tiny fishing harbour on the western edge of Laganas Bay, a few minutes from the busy resort of Laganas but much calmer. A small whitewashed chapel stands by a large rock topped with a Greek flag, and boats leave from a sheltered quay where a shaded waiting area lets you relax until boarding. It is the natural starting point for a Zakynthos glass-bottom boat trip, since the marine park, Marathonisi and the Keri coast are all within a short ride.

With the transfer option, our driver brings you here from your accommodation and takes you back after the cruise, so you do not need a car or a taxi. The whole half day takes about five hours with the transfers, and the cruise itself around three hours. Wear swimwear under your clothes so you are ready for the stops.

Cameo Island

Right beside the harbour lies Cameo Island, a small pine-covered islet linked to the shore by a wooden footbridge hung with white fabric. Local history says it was cut off from the coast by an earthquake in the seventeenth century, and its rocky edges, sea-facing terraces and clear water have made it one of the island's favourite photo backdrops.

The boat pauses here at the start of the tour so you can photograph the bridge and the islet from the water, where the whole scene fits in one frame. Your guide explains the islet's story before the boat heads out into Laganas Bay. Walking onto Cameo Island is a separate visit with its own entry fee and is not part of this cruise.

Laganas Bay and the loggerhead turtles

Laganas Bay is protected as the National Marine Park of Zakynthos because its beaches are among the most important nesting sites for the loggerhead sea turtle in the Mediterranean. Adults can grow to around a metre long and weigh over 100 kilograms, and they spend most of their lives at sea, coming up every few minutes to breathe. Turtle spotting in Zante is at its best from May to October, when the females gather off the nesting beaches.

The glass-bottom boat moves slowly over the shallow parts of the bay while the guide and captain scan the surface. Inside, the glass floor shows sea grass meadows, fish and the sandy seabed; outside, you may see a turtle's head break the surface close to the boat. The crew keeps a respectful distance and never chases the animals, following the rules of the park.

The Keri Caves

At the south-western tip of Zakynthos, white limestone cliffs plunge into deep water beneath Cape Keri, and the sea has carved them into a chain of caves and arches. The light bouncing off the pale rock turns the water inside an electric blue, and the coastline is so steep that the caves can be reached only from the sea. Close by, the village of Keri is known for natural pitch springs mentioned by the ancient historian Herodotus.

The boat stops at the caves for about 30 minutes for a guided look and a swim. This is the best place on the tour for snorkelling, so bring your own mask and snorkel, as gear and towels are not provided. Non-swimmers can stay on board and watch the fish through the glass floor while the boat floats by the cave mouths.

Marathonisi beach (Turtle Island)

Marathonisi is the small wooded island in the middle of Laganas Bay whose shape, seen from the shore, resembles a turtle. Its beach of soft golden sand and shallow turquoise water is one of the protected nesting sites of the loggerhead turtles, which is why it is often called Turtle Island. If you have wondered how to get to Marathonisi, the answer is only by boat, and this tour includes a landing.

You have about 50 minutes to swim, relax on the sand or stay aboard and watch for turtles from the deck. Visitors keep near the water's edge and away from the marked nests, umbrellas are not allowed and the beach closes at night to protect the turtles. Afterwards the boat returns to Agios Sostis, and the transfer takes you back to your hotel.