The park is located within the Minamiboso Quasi-National Park, a protected coastal region.
The underwater observation tower is one of the few structures in Japan that allows direct viewing of a natural reef without the use of a submarine or scuba gear.
Katsuura's unique location at the meeting point of the Kuroshio (warm) and Oyashio (cold) currents creates a micro-climate that supports over 100 species of fish.
The water clarity is heavily dependent on weather conditions and recent tide movements, making the underwater view different every day.
The structure is designed to withstand the strong wave action common in the exposed waters of the Boso Peninsula.
Katsuura Marine Park features a unique underwater observation tower situated 60 meters offshore, connected to the mainland by a pedestrian bridge. The facility allows visitors to observe marine life in the natural environment of the Pacific Ocean at a depth of 8 meters below sea level. The observation deck provides panoramic views of the coastal cliffs and the Katsuura Bay. The underwater windows offer visibility into the complex Katsuura reef ecosystem, which acts as a transition zone between warm and cold currents. This convergence of currents supports a high diversity of tropical and temperate fish species year-round. An on-site museum exhibits specimens and educational information about the local sea life found within the surrounding coastal waters.
The mid-point of the pedestrian bridge looking back toward the observation tower against the backdrop of the Pacific Ocean.
Check the daily 'visibility' rating on the park's website before departing, as turbidity can obscure underwater views.
Bring a windbreaker or outer layer, as the pedestrian bridge and the observation deck are exposed to strong Pacific winds.
Combine your visit with a walk along the adjacent rocky coastline for views of the unique strata of the Boso Peninsula.
Avoid visiting immediately after a heavy rainstorm, as sediment runoff significantly reduces the underwater visibility.
Subject to temporary closure during extreme weather conditions or high sea states; check official updates prior to arrival.
