The cave is part of the Misaki Formation, which dates back to the Miocene epoch, approximately 10 to 15 million years ago.
The surrounding 'Umanose' ridge is officially recognized as a scenic rock formation within the Kanagawa Prefectural Park.
The cave floor is subject to significant tidal variation and can become completely submerged or inaccessible during high tide.
The volcanic ash layers visible in the cave walls provide a record of ancient submarine volcanic eruptions in the region.
Umanose Cave is a prominent sea cave located on the southern coast of Jogashima, a small island at the tip of the Miura Peninsula in Kanagawa Prefecture. The cave was formed through the natural erosion of tuffaceous rock strata caused by persistent wave action from the Pacific Ocean. Its name, meaning 'horse's back,' refers to the ridge-like rock formation surrounding the cavern entrance. Visitors can traverse the rocky coastline to reach the cave mouth, which provides a natural frame looking out toward the horizon. The site is a core feature of the Jogashima Park area, characterized by rugged wave-cut benches and exposed geological layers. Visitors should be aware that the terrain is uneven and slippery due to tidal activity. It serves as a significant spot for observing coastal erosion patterns and marine fossil layers embedded in the cliffside.
From inside the cave looking out toward the ocean to frame the sea through the archway.
Wear footwear with high-grip rubber soles as the coastal rock surfaces are frequently wet and slick.
Check local tide tables before visiting to ensure the cave entrance is not submerged by the incoming tide.
Bring a headlamp or flashlight if you intend to inspect the deeper, narrower crevices of the rock formations.
Attempting to traverse the rocky shoreline during high tide or heavy surf conditions.
Access may be restricted during severe weather, high storm surges, or tsunami warnings.
Do not climb on unstable cliff faces or remove geological samples from the site.
