Kasaoka Islands: Enjoying Dinosaur Island, Horseshoe Crab Village, and Seto Inland Sea Multi-Island Beauty

Islands dotting the blue sea, cats living at ease on the islands, and the living fossil horseshoe crab unchanged since ancient times. The Kasaoka Islands, spreading offshore from Kasaoka City, Okayama, are an archipelago full of the multi-island beauty unique to the Seto Inland Sea and the distinctive charm of each island. Seeking peaceful island time and rich nature, set out on an island-hopping trip in the Seto Inland Sea.

Highlights

The Kasaoka Islands are an archipelago of about 30 large and small islands spreading offshore from Kasaoka City, Okayama. Several of them are inhabited, and each has nurtured its own culture, nature, and history. The multi-island beauty of islands scattered across the calm Seto Inland Sea is a loveliness unique to this region. You reach them by boat from the mainland and can also enjoy a voyage from island to island.

The island beloved as the cat island is Manabe Island. All over the island you meet friendly cats living at ease, a paradise for cat lovers. It retains the streets and old-fashioned atmosphere of an old fishing village and has served as a film location. Kitagi Island, the stone island, flourished as a producer of granite, and Kitagi stone is known for having been used in many structures, including the stonework of Tokyo Station and the torii gate of Yasukuni Shrine.

The Horseshoe Crab Village

Kasaoka is known nationwide as a place associated with the horseshoe crab, also called a living fossil. Having survived almost unchanged for some 200 million years, the horseshoe crab is a National Natural Monument. Conservation efforts have continued for the former breeding ground in Kasaoka Bay. The city has a museum where you can learn about horseshoe crabs and understand their ecology and evolutionary history. Evoking ancient romance, the horseshoe crab symbolizes the richness of Kasaoka nature.

Seasonal Enjoyment

Island hopping is recommended from spring to autumn, when the sea is calm and comfortable. Agriculture using the mild climate is also active, with figs grown in Kasaoka and Kamogata as a specialty. Fresh Seto Inland Sea seafood can also be enjoyed. In summer the blue of the sea shines, and the peaceful island time feels all the more pleasant.

Access and Basic Information

The mainland base is Kasaoka Station on the JR Sanyo Main Line, and you can reach Kasaoka Port from the station by taxi or on foot. From Kasaoka Port, scheduled ferries cross to each island, taking about 20 to 60 minutes depending on the island. Getting around the islands is mainly on foot or by bicycle. Because ferries are infrequent, checking the timetable is essential for a day trip.

Practical Travel Notes

• Ferries are infrequent, so always check the round-trip times in advance.
• Some islands have few large shops, so bringing drinks and light snacks is reassuring.
• Islands such as Manabe have many slopes and narrow lanes, so comfortable shoes are recommended.
• Cats are wild creatures. Do not needlessly feed or chase them; watch over them quietly.
• Ferries may be canceled due to weather, so keeping a backup date in mind is reassuring.

A Word of Advice

If touring several islands in one day, the trick is to plan around the ferry times. Combining islands of different character, such as the cat island of Manabe and the stone island of Kitagi, lets you savor the multi-island beauty of the Seto Inland Sea more deeply.

📚 Sources

This article draws on tourism guidance from Kasaoka City, published information on the Kasaoka Islands such as Manabeshima and Kitagishima, guidance from the Kabutogani (Horseshoe Crab) Museum, sailing information from the ferry operators serving Kasaoka Port, and information from JR West, which operates the JR Sanyo Line. Descriptions of Kitagi stone and the horseshoe crab (a national Natural Monument) follow the facility and on-site guidance. Ferry frequency and operating status change with sea conditions, so please confirm details on each operator or the official Kasaoka City sources before visiting.

Visitor Checklist

• Estimated time: Ferries from Kasaoka Port take about 20 to 60 minutes depending on the island. To tour several islands in a day, plan around the boat times.
• What to prepare: Some islands have few large shops, so bring drinks and snacks.
• What to bring: Manabeshima and others have many slopes and narrow lanes, so comfortable shoes are recommended; on the islands, get around on foot or by bicycle.
• Checking sailings: Ferries are infrequent, so always confirm round-trip times in advance; sailings may be cancelled in bad weather, so keep a backup day in mind.
• Respecting nature: The cats are wild animals, so do not feed or chase them; watch over them gently.

Practical Information for Your Visit

• Opening hours of the Kasaoka City Horseshoe Crab Museum: 9:00-17:00 (last admission 16:30). The adjoining Dinosaur Park is also open 9:00-17:00 (closed on the museum's closing days)
• Admission (individual): 500 yen for adults, 300 yen for high school students, 200 yen for elementary and junior high school students from outside the city. Note: revised downwards on April 1, 2026
• Closed: Mondays (the following day when Monday is a public holiday or a substitute holiday), the day after a public holiday, and the year-end and New Year period (December 29 to January 3). However, the museum opens every day from March 25 to April 10, from April 27 to May 10, and from July 15 to August 31
• Getting to the museum: From JR Kasaoka Station, take the Ikasa Bus Company Konoshima Line and get off at Kabutogani Hakubutsukan-mae. By car, 9.7 km from the Kasaoka IC on the Sanyo Expressway
• Where to board the boats to the islands: The passenger boats that call at all of the islands depart from Sumiyoshi Port. Note that this is a different landing point from Fushikoshi Port, where the ferries arrive and depart
• Cars cannot be carried on board: Cars may not be taken onto the passenger boats. Bicycles, mopeds and motorcycles can be brought aboard as special baggage for an additional fee

(Sources: Kasaoka City official website, General Guide to the Horseshoe Crab Museum (admission, access and more), updated April 1, 2026 / Kasaoka City Tourism Association, Kasaoka Kanko WEB, Scheduled Passenger Boat Timetable)