Zakynthos Glass Bottom Turtle Boat Tour: Keri Caves & Islands

Swim inside sea caves and watch nesting turtles from a glass-bottom boat

A 3-hour glass bottom boat tour departing from Agios Sostis port takes you to Keri Caves, Marathonisi Island and Laganas Bay to watch caretta caretta turtles in their natural habitat. The boat has a glass bottom so you can see underwater life while cruising, and includes two designated swim stops—one inside the Keri Caves with snorkeling opportunity, and one at Marathonisi's private beach where turtles nest. A live English or Greek-speaking guide leads the tour; children from age 3 are welcome, and private transportation is included.

Step-by-step itinerary

Glass Bottom Boat Tour and Swimming

• Depart from Agios Sostis port
• Spot turtles around Laganas Bay
• Swim at Keri Caves
• Swim at Marathonisi Island
• Visit Cameo Island for photos

The Experience

The boat leaves Agios Sostis port and heads first to Cameo Island for photos, then moves into the National Marine Park of Zakynthos where the glass bottom lets you watch the seabed without getting wet. After about half an hour of cruising and turtle spotting around Laganas Bay—where you'll have time to photograph the caretta caretta turtles in the water—the tour reaches its first swim stop at Keri Caves. The caves themselves rise from the water in sheer white cliffs, and you swim inside them in emerald-colored water; bring your own snorkeling kit if you want to see the underwater world up close.

The second swim stop is at Marathonisi Island, the private beach where loggerhead turtles actually nest their eggs. You get 45 to 60 minutes here to swim, sunbathe and take pictures. The island sits in shallow water and the beach is small, so the whole stop has a quieter feel than a crowded public beach. By the end of the tour you've been in the water twice, seen the turtles from both the boat and the sea, and spent time in one of the Mediterranean's most distinctive geological features.

What’s included

• Private transportation.
• live guide in English or Greek.
• glass bottom boat access for the full cruise.
• two swim stops at Keri Caves and Marathonski Island.
• turtle spotting time around Laganas Bay.
• photo opportunity of caretta caretta turtles in their natural habitat.

Good to know

Easy physical levelPublic transport nearbyNot for pregnant travelersNot for heart conditionsNot for back problems

Operated by Luxury Island Events

Is this one for you?Book this if you want to watch turtles from the boat and swim at two stops—the glass bottom lets you see underwater without diving, while Marathonisi and Keri Caves offer different water experiences in one trip.

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Top questions

How close do you actually get to the turtles on this tour?

The glass bottom boat sails very close to the turtles for about half an hour around Laganas Bay so you can photograph them in their natural habitat. You'll also be in the water at Marathonisi Island, where the turtles nest, giving you another chance to spot them while swimming.

What's the difference between the glass bottom boat and a regular boat?

The glass bottom lets you see the seabed and marine life while the boat is moving, without needing to get in the water or lean over the side. It's a continuous view during the cruise portions of the tour, separate from the two designated swim stops.

Can I snorkel at both swim stops?

You can snorkel at Keri Caves if you bring your own kit—the crystal water there is good for seeing the underwater world. At Marathonisi Island you're free to swim and explore, though snorkeling is not the main focus of that stop.

Is the 3-hour tour just time in the water, or does that include sailing?

The 3 hours includes all sailing time between stops, the two swim stops, and turtle spotting. The actual time spent swimming at each location is part of that total, not added on top.

What age can children join this tour?

Children are welcome from age 3. The tour includes private transportation, and the glass bottom boat and swim stops are accessible for young swimmers with supervision.

Do I need to bring snorkeling gear?

Snorkeling kit is not included, so you'll need to bring your own if you want to snorkel at Keri Caves. At Marathonski Island you can swim without it.