Shirasaki Ocean Park 白崎海洋公園

The park’s geological history

The limestone formations are masses of calcium carbonate formed through the accumulation of biological matter, such as shells and coral. They contain fossils of ancient and extinct marine organisms, including crinoids (also known as sea lilies or feather stars) and fusulinids, extinct single-celled organisms with shells. The presence of fusulinids indicates that the karst topography of the park and surrounding coastline is at least 250 million years old, as this is when they are considered to have become extinct. Fusulinida fossils range from several millimeters to 1 centimeter and resemble grains of rice. In horizontal cross-sectional views, they have a spiral form.

Limestone excavation

Signs of Shirasaki Ocean Park’s past are visible in the appearance and form of the limestone outcrops and in several disused caves that remain. The park was a site for limestone excavation between 1897 and 1972. The limestone excavated there was used in construction and as a raw material in the manufacture of fertilizer and cement. For a brief period during World War II, the excavated caves were used as a secret military base for the storage and launch of crewed torpedoes.

Activities and experiences

The lookout built atop the limestone formations on the western perimeter of the park offers a close-up view of a karst environment. The rock has been eroded by the rain, and calcium-tolerant vegetation grows in clusters between jagged ridges. On a clear day, Awaji Island and the eastern coast of Shikoku are sometimes visible across the Kii Strait. Walking the perimeter of the park, with a stop at the lookout, takes about 30 to 60 minutes.

The park is a popular destination for camping and diving. At the campground, there are both tent sites and cabins with kitchens and basic appliances. Staying overnight offers stargazing opportunities, as the remote location and the surrounding limestone formations block light pollution. The park and its surroundings also have some dive sites, including a beginner-friendly beach-entry point and a boat-entry underwater sea cave exclusively for advanced divers. Dives can be arranged through local diving schools.

The limestone formations along the Shirasaki Coast have long captured the imagination of travelers and seafarers, and are referenced in an eighth-century poem. Shirasaki Ocean Park covers a 1-kilometer stretch of headland on this celebrated coast. A lookout built atop one of the formations in the park affords views of the coastline and its distinctive karst topography.

The limestone formations date back 250 million years to the Permian Period. These masses of calcium carbonate are made of biological matter, such as shells and coral, that accumulated over centuries. A walk alongside the formations in the park may reveal fossils of crinoids (also known as sea lilies or feather stars) and fusulinids (extinct single-celled organisms) embedded in the rock. It takes about 30 to 60 minutes to walk around the park and visit the observatory.

The park facilities include camping grounds and a visitor center that sells produce and other local specialties, such as citrus fruit juices. Meals are available at the restaurant in the visitor center, including akamoku rice bowls. Akamoku is a species of brown macroalgae harvested locally. It is typically seasoned with soy sauce and served on top of rice with other ingredients such as whitebait, avocado, egg, and perilla leaf.