Agios Sostis: Marathonissi, Keri Caves, and Turtle Spotting

A Close Look at Agios Sostis: Marathonissi, Keri Caves, and Turtle Spotting

This boat tour around Zakynthos offers a taste of the island’s natural beauty, wildlife, and seascape in a compact 3-hour trip. Departing from Laganas, it takes you past rugged limestone caves, a tiny turtle-breeding island, and into the clear waters where loggerhead turtles often appear. The standout features? The chance to see these magnificent creatures in their actual habitat and the stunning scenery of the Keri Caves.

Two things I really appreciate about this experience are its affordable price of just over $28 per person, which includes entry to the island and swimming stops, and the glass-bottom boat that lets you peek beneath the waves without getting wet. It’s a clever way to appreciate the marine life and rock formations without the need for snorkeling gear or deep diving. On the other hand, a possible drawback is that swimming inside the caves isn’t permitted, which might disappoint those eager to explore every crevice up close.

This tour strikes a good balance between fun, education, and sightseeing — especially for first-timers or families. But if you’re after a more extensive or private experience, you might want to explore other options. Still, for a quick, well-organized trip that offers authentic encounters with the area’s iconic turtles and caves, it’s a solid choice.

Key points / Takeaways

• Cost-effective: At just over $28, this tour offers a lot of value, including multiple stops and the chance to see turtles in their natural environment.
• Wildlife spotting: The primary draw is the opportunity to see endangered Caretta Caretta turtles in the wild, which many reviews highlight as a memorable highlight.
• Comfortable ride: The boat has both shaded and sunbathing areas, making it flexible for your preference and weather conditions.
• Unique underwater views: The glass-bottom boat provides a window into the marine world without the need for snorkeling—an excellent feature for casual observers or those wary of water.
• Authentic, scenic stops: Expect to visit the Keri Caves with their striking limestone formations and Marathonisi, the tiny island with a protected turtle nesting beach.
• Limited cave access: While the caves are beautiful, swimming directly inside isn’t allowed, which might leave some wishing for a more immersive cave experience.

Discovering Zakynthos’ Marine Wonders — A Deep Dive into the Tour

Choosing this tour from Laganas is a smart way to combine sightseeing, wildlife watching, and light adventure all within a short window. The tour lasts roughly three hours, which makes it perfect if you’re on a packed schedule or want a quick taste of Zakynthos’ coastal treasures. Depart from the Agios Sostis harbor, where you’ll spot the Nautilos flag in front of the boat—an easy marker to find. The crew, led by a friendly captain, will welcome you aboard, and you can settle into your preferred spot, whether shaded or sun-drenched.

The Journey Begins — A Scenic Ride Out to the Marine Park

Once underway, you’ll quickly feel the breeze and see the island’s rocky coastline whiz past. The boat’s design balances comfort with practicality; the rear sundeck is perfect for soaking up the sun, while shaded seating is great for those wanting relief from the Greek sun. As you sail toward the Keri Caves, keep your camera ready—this dramatic limestone landscape is a favorite for photos.

Many reviews praise the smooth ride and the captain’s engaging commentary — some say the guides are knowledgeable and fun, making the trip more than just a scenic boat ride. While the boat is spacious enough for a handful of people, it’s best to book in advance during peak season to ensure a spot.

Exploring the Keri Caves — Nature’s Limestone Art

The Keri Caves are the star of this trip. Accessible only by boat, they form a stunning natural marvel with their towering limestone walls and hidden coves. You’ll stop here for a swim in the Keri Cave’s area or in Oasi Bay, where the blue light filtering through limestone creates a magical ambiance.

A common experience, echoed by multiple reviewers, is the joy of floating in pristine waters and snapping photos of the caves’ unique formations. But note: swimming inside the caves is not permitted, so don’t plan to explore every nook up close. Still, the view from the water’s surface is breathtaking enough.

Marathonisi Island — Turtle Paradise

Next stop: Marathonisi, affectionately called “Turtle Island” by many. This tiny island is protected as a breeding ground for the endangered loggerhead turtles. As you approach, you’ll see a small beach where turtles come ashore to lay eggs. This is a highlight for many guests—seeing these gentle creatures in their natural habitat is a rare treat, often described as “incredible” in reviews.

The island also offers some free time for exploration or relaxing at a bar, where you can purchase snacks, drinks, and ice cream. It’s a perfect spot to stretch your legs and enjoy a drink while watching the boats bobbing nearby. Keep in mind—the beach is limited and protected, so don’t expect a full day of lounging or sunbathing here.

What the Tour Includes — Is It Worth the Price?

For $28.12, the tour includes a glass-bottom boat ticket, stops at Marathonisi, Keri Caves, and Oasi Bay for swimming. It’s a simple, straightforward package that offers genuine value—especially considering the chance to see turtles and stunning caves without needing your own boat or snorkeling gear.

However, food and drinks are not included but available for purchase on Marathonisi, and there’s no option for hotel pickup or drop-off. This might be a challenge if you’re staying far from Laganas, but most travelers find the meeting point at Agios Sostis manageable.

Trip Tips and Considerations

• Bring sunscreen, hats, and sunglasses — the Greek sun can be intense, especially on the water.
• Snorkeling gear is recommended if you want to explore the shallow waters more closely, though the tour itself doesn’t include snorkeling.
• Luggage or large bags aren’t allowed on the boat—pack light.
• Arrive early to secure a good spot and to meet the captain, who is often praised for his friendly attitude.
• Timing varies, so check availability when booking to pick a start time that suits your plans.

Who Will Love This Tour?

If you’re interested in wildlife, especially sea turtles, this trip offers a rare, up-close view. It’s also ideal for those who appreciate stunning coastal scenery and want a relaxing, well-paced outing. Families with children, travelers seeking a brief adventure, or first-time visitors to Zakynthos will find this tour especially accessible and rewarding.

Who Might Want More?

Travelers craving more extensive cave exploration or private tours may find this experience a bit limited, especially since swimming inside the caves isn’t allowed. Also, if you’re seeking a full day or a more secluded experience, other options might be more suitable.

The Sum Up

This boat tour from Laganas to the Keri Caves and Marathonisi Island offers a solid introduction to Zakynthos’ spectacular coast and its most famous residents—the loggerhead turtles. It combines scenic views, wildlife encounters, and a chance to see some of the island’s most iconic limestone formations in just a few hours, making it an excellent choice for a quick, affordable adventure.

You’ll love the opportunity to see turtles in their natural environment and the beautiful caves—both features that set this tour apart. The glass-bottom boat makes marine observation accessible and fun, especially for those who aren’t keen snorkelers. The guides, often praised for their friendliness and knowledge, help make the trip memorable.

That said, this experience isn’t for those wanting a full-day, private, or more immersive cave or snorkeling adventure. It’s best suited for visitors who want a taste of Zakynthos’ natural beauty without breaking the bank or spending hours on the water.

For the price, convenience, and the chance to see wildlife in action, it’s a tour I’d recommend to anyone looking for a fun, authentic, and budget-friendly way to experience the island’s marine park.

FAQ

Is transportation included from my hotel?
No, hotel pickup and drop-off are not included. You’ll need to get to the Agios Sostis harbor in Laganas for the start of the tour.

What should I bring on the boat?
Bring sunglasses, a sun hat, swimwear, a towel, sunscreen, snorkeling gear if you have it, and any snacks or drinks you might want while on the island.

Can I swim inside the caves?
No, swimming inside the caves is not permitted. However, you can enjoy swimming in the areas near the caves like Oasi Bay.

How long does the tour last?
It lasts approximately 3 hours, with time allocated for sightseeing, swimming, and exploring Marathonisi.

Will I see turtles?
Many reviews mention spotting turtles during the trip, which is a major highlight. While no sightings are guaranteed, the tour is designed around their habitat.

Is it suitable for children or families?
Yes, it’s a family-friendly tour, especially if your children enjoy boat rides, wildlife, and scenic views. Just be mindful of sun exposure and bring appropriate gear.

This trip offers a balanced mix of wildlife, scenery, and relaxing fun—ideal for travelers who want a memorable taste of Zakynthos without overcommitting.