Agios Sostis offers an unforgettable adventure that combines stunning natural scenery with unique wildlife encounters. Visitors can embark on a glass-bottom boat tour to marvel at the vibrant marine life and swim in the turquoise waters of the Keri Caves. The journey also includes a visit to Marathonissi Island, a protected breeding ground for loggerhead turtles, where guests can explore pristine beaches and learn about marine conservation efforts. This all-encompassing experience promises to leave a lasting impression on those who seek to enjoy the captivating beauty of this remarkable destination.
Key Points

- The tour departs from Agios Sostis harbor and visits Marathonissi Island, a breeding ground for loggerhead turtles, as well as the renowned Keri Caves.
- The glass-bottom boat provides mesmerizing views of the marine life, and guests have the opportunity to swim at the Keri Caves.
- The tour includes hotel pickup and drop-off, ensuring convenience, and offers free cancellation up to 24 hours in advance.
- Guests can explore the pristine beaches of Marathonissi Island and observe the nesting activities of the loggerhead turtles during the tour.
- The tour is highly rated for its excellent transportation, value for money, and the captain’s care for the turtles, providing an immersive and engaging experience.
Tour Overview

The tour from Laganas includes visits to the Keri Caves, Marathonisi Island, and opportunities for turtle spotting, with a duration of 3 hours and a starting price of €63 per person.
Travelers can enjoy free cancellation up to 24 hours in advance, and the tour is available in both Greek and English.
The glass-bottom boat provides views of the underwater life, and visitors will have the chance to swim at the Keri Caves, which are only accessible by boat.
Marathonisi Island is a known breeding ground for loggerhead turtles (Caretta Caretta), and guests will have free time to explore the island or purchase snacks and drinks.
You can also read our reviews of more tours and experiences in Agios Sostis.
Experience Highlights

A glass-bottom boat offers visitors mesmerizing views of the underwater marine life during the tour. Guests can swim at the renowned Keri Caves, which are only accessible by boat. The tour also includes a visit to Marathonisi Island, a breeding ground for the loggerhead turtle (Caretta Caretta). While on the island, visitors have free time to explore or purchase snacks and drinks.
| Experience Highlights | |
|---|---|
| Glass-bottom boat | Views of marine life |
| Swim at Keri Caves | Accessible only by boat |
| Visit Marathonisi Island | Breeding ground for loggerhead turtles |
| Free time on Marathonisi | Explore or purchase snacks/drinks |
Tour Inclusions

The tour includes a glass-bottom boat ticket, a visit to Marathonisi Island, and a swim stop at the Keri Caves.
Guests will have the chance to gaze upon the underwater marine life through the glass-bottom boat.
The tour also takes visitors to Marathonisi Island, a breeding ground for the loggerhead turtles (Caretta Caretta). Here, they’ll have free time to explore the island or purchase snacks and drinks.
Plus, the tour offers a swim stop at the picturesque Keri Caves, which are only accessible by boat.
Hotel pickup and drop-off are included, ensuring a seamless experience.
With these comprehensive inclusions, the tour provides an immersive and memorable exploration of the area’s natural wonders.
Logistics and Recommendations

Travelers can meet at the Nautilos Flag located at the Agios Sostis harbor to begin the tour. For the excursion, visitors are recommended to bring items such as sunglasses, swimwear, towels, sunscreen, and snorkeling gear. However, large bags and luggage are not allowed on the tour. Plus, beach access on Marathonisi Island may be limited due to conservation efforts for the loggerhead turtles.
| Meeting Point | Recommended Items | Important Information |
|---|---|---|
| Nautilos Flag at Agios Sostis harbor | Sunglasses, swimwear, towel, sunscreen, snorkeling gear | No luggage or large bags allowed, limited beach access on Marathonisi |
Customer Ratings and Feedback

Based on 107 reviews, the tour has an overall rating of 4.6 out of 5 stars.
Customers particularly praised the excellent transportation (4.7/5) and the value for money (4.7/5) that the tour offers.
Positive feedback also highlights the captain’s care for the turtles and the engaging tour experience, though some initial chaos with boat assignments was noted.
The stunning scenery and wildlife sightings, including the opportunity to see loggerhead turtles, seem to have made up for any minor organizational issues.
Discovering Keri Caves

Accessible only by boat, the Keri Caves offer visitors a captivating underwater adventure, where they can swim through the serene, turquoise waters and marvel at the cave formations. Submerged within the crystal-clear depths, these enchanting caverns reveal a hidden world teeming with marine life.
Visitors can:
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Explore the intricate rock structures, sculpted by centuries of erosion
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Spot schools of vibrant fish darting through the sunbeams
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Dive deeper to uncover the caves’ mysterious underwater chambers
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Relax and rejuvenate in the tranquil, natural environment
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Capture breathtaking underwater photos to commemorate the experience
This unique opportunity allows travelers to enjoy the remarkable beauty of Keri Caves, creating memories that will last long after their Agios Sostis adventure.
Exploring Marathonisi Island

The tour takes visitors to Marathonisi Island, a renowned breeding ground for the loggerhead turtle (Caretta Caretta), where they can observe these majestic creatures in their natural habitat.
This uninhabited island is accessible only by boat, offering a unique opportunity to explore its pristine beaches and witness the turtles’ nesting activities.
Guests will have free time to wander the island, taking in the stunning scenery and perhaps even spotting a turtle or two.
While access to the beaches is limited due to conservation efforts, visitors can still enjoy the island’s natural beauty and the chance to learn more about these incredible marine creatures.
The tour provides an unforgettable glimpse into the delicate ecosystem of Marathonisi Island.
Spotting Loggerhead Turtles

Visitors’ chances of spotting loggerhead turtles (Caretta Caretta) are highest on Marathonisi Island, a pristine breeding ground for these majestic creatures. During the boat tour, guests have the opportunity to observe the turtles in their natural habitat. The island’s protected status and limited access ensure minimal disturbance to the turtles.
Spotting these endangered species is a truly remarkable experience, offering insights into their behavior and conservation efforts. The tour guides are passionate about educating visitors and ensuring a respectful encounter.
Some of the reasons why turtle spotting on Marathonisi is so special include:
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Witnessing the turtles’ graceful movements in the clear waters
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Learning about their nesting habits and life cycle
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Supporting conservation efforts through responsible tourism
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Appreciating the fragility and importance of these threatened ecosystems
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Creating lasting memories of an unforgettable wildlife encounter
Frequently Asked Questions
What Is the Cancellation Policy for This Tour?
The tour has a free cancellation policy up to 24 hours in advance. Customers can cancel their booking without incurring any penalties if they notify the provider at least a day before the scheduled departure.
Are There Any Age Restrictions for This Tour?
There are no age restrictions for this tour. The tour is open to participants of all ages. Children can join the tour, and families are welcome to participate in this boat excursion.
Can I Bring My Own Snacks and Drinks on the Tour?
Yes, guests can bring their own snacks and drinks on the tour. However, food and drinks are also available for purchase on Marathonisi Island during the free time. The tour includes hotel pickup and drop-off.
Is There a Minimum Number of Participants Required for the Tour to Run?
The tour has no minimum number of participants required. It runs regularly, and travelers can join regardless of group size. The tour operator is flexible and accommodates individual bookings as well as larger groups.
Can I Extend My Time on Marathonisi Island if I Wish?
While the tour includes a visit to Marathonisi Island, travelers can’t extend their time there beyond the scheduled free time. The tour has a fixed itinerary and schedule that doesn’t allow for independent exploration of the island.
Recap
Agios Sostis offers a unique blend of natural wonders and wildlife encounters.
Visitors can marvel at the vibrant marine life through a glass-bottom boat tour, explore the stunning Keri Caves, and discover Marathonissi, a protected breeding ground for loggerhead turtles.
This unforgettable adventure showcases the region’s scenic beauty and commitment to marine conservation, making it a must-do activity for those seeking a truly immersive experience.
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