Keri Caves glass-bottom boat tour: Zakynthos sea turtle habitat

The glass bottom lets you watch the seabed while the boat floats above it.

A 3-hour glass-bottom boat cruise from Agios Sostis Harbor explores the southern coastline of Zakynthos, passing Cameo Island and stopping at Marathonisi Island for swimming and the dramatic Keri Caves. The boat carries a maximum of 16 guests with a professional captain and English-speaking guide, and includes life jackets and a safety briefing.

Step-by-step itinerary

Glass-bottom boat tour Zakynthos coast

• Depart from Agios Sostis Harbor
• Cruise across Laganas Bay
• Explore Keri sea caves
• Swim near Keri Caves
• Stop at Marathonisi Island for swimming
• Photo stop at Cameo Island

The experience

Keri Caves are the centerpiece: the boat approaches limestone formations and natural arches carved into white cliffs, with the water so clear you can see the seabed through the glass bottom. The route crosses Laganas Bay, part of the National Marine Park of Zakynthos and a protected nesting habitat for loggerhead sea turtles: sightings depend on conditions and are not guaranteed. You'll pass Cameo Island, a small landmass formed after a 17th-century earthquake, on the way back.

Two swimming stops break up the cruise. One is near Marathonisi Island, recognizable by its turtle shape, where you can float in the clear water and take photos. The second is in a sheltered area close to the Keri Caves themselves, weather permitting, so you experience the dramatic coastline from the water. The boat's glass bottom works throughout the journey, giving you a view of the marine landscape without leaving your seat.

The group stays small, maximum 16 people, so the captain and host can manage the boat and the stops without the crowding of larger tours. Life jackets are provided and a safety briefing happens before departure. You'll need to arrange your own transport to Agios Sostis Harbor. Public transportation options are available nearby.

What’s included

• English-speaking tour guide.
• glass-bottom boat cruise.
• fuel and local taxes.
• safety briefing and life jackets.
• swimming stops at Marathonisi Island and near Keri Caves.

Before you book

Lasts 3h, runs Friday at 10:00 and 13:00, from € 24.99 per person, with a live guide in English and with free cancellation up to 24 h before.

Days and timesFridayDepartures at 10:00 and 13:00

Book up to2h before

AgesAdult (18 and older) · Under 18: can't be booked

GroupUp to 23

Live guideEnglish

Meeting point and pickupNo hotel pickup: you go to the meeting point. Ends back at the starting point.

Cancellation and refundsFree cancellation up to 24 h before the start. After that, no refund.

Prices and times updated 2 days ago

Good to know

Low physical effortPublic transport nearbyNot recommended during pregnancyNot recommended with heart problemsNot recommended with back problemsInfants must sit on laps

Operated by Escape

Is this one for you?Three hours leaves room for other activities earlier or later in the day, but not enough for a full second excursion. Book this if you want the Keri Caves and a swim without committing the whole afternoon.

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Top questions

Can I swim at both Marathonisi Island and the Keri Caves on the same tour?

Yes. Marathonisi Island has a dedicated swimming stop, and a second swimming stop happens in a sheltered area near the Keri Caves, weather permitting. Both are part of the standard itinerary.

What are the chances of seeing sea turtles during the tour?

Loggerhead sea turtles nest in Laganas Bay, which the boat crosses, but sightings depend on natural conditions and are not guaranteed. The area is a protected marine habitat, so the environment supports them year-round.

How does the glass bottom of the boat work?

The boat has a glass-bottom section that lets you see the seabed and marine life below the waterline while you remain seated on the boat. It operates throughout the cruise, giving you an underwater view without entering the water.

What is Cameo Island and why do we stop there?

Cameo Island is a small island formed after a 17th-century earthquake. The boat passes it on the return journey, and it offers a photo opportunity from the water.

Is this tour suitable for someone with mobility concerns?

The tour is not recommended for travelers with spinal injuries or poor cardiovascular health. It is suitable for all other fitness levels. You should discuss any mobility concerns with the operator before booking.