Starting from Agios Sostis port, you will have a memorable experience visiting various landmarks and natural wonders along the coast. Here is a brief breakdown of the itinerary you mentioned:

1. Departure from Agios Sostis port: The tour starts from this picturesque port on Zakynthos Island.

2. First turtle spotting: Zakynthos is known for its loggerhead sea turtles, and it's a great experience to spot these magnificent creatures in their natural habitat.

3. Visit Turtle Island: Turtle Island, also known as Marathonisi, is a small island off the coast of Zakynthos where turtles often nest. It's a beautiful place to visit and learn more about these fascinating animals.

4. Explore Marathonisi caves: The caves around Marathonisi are stunning and offer a unique opportunity to explore the island's natural beauty.

5. Arch of Keri: The Arch of Keri is a natural rock formation that is a popular sightseeing spot in Zakynthos.

6. Swimming at Keri caves: Keri caves are known for their crystal-clear waters and are perfect for swimming and snorkeling.

7. Explore the coves along the coast: The coastline of Keri is dotted with beautiful coves that are worth exploring.

8. Mizithres Rocks: Finally, the tour culminates at the iconic Mizithres Rocks, where you can witness one of the most beautiful sunsets in Greece. The view as the sun disappears into the big blue sea is truly breathtaking.

Overall, this sunset tour promises to be a memorable and magical experience, allowing you to appreciate the natural beauty and charm of Zakynthos Island. Enjoy your journey!