Kushiro Wetlands

Kushiro Wetland: Japan's Vast Primeval Marshland Where Cranes Dance

In the far east of Hokkaido, where the Pacific winds sweep across an endless horizon of reeds, lies a landscape unlike anywhere else in Japan. Kushiro Wetland (Kushiro Shitsugen) is the country's largest marshland, a primordial expanse of waterways, peat bogs, and grasslands that has been forming for roughly three thousand years. Stretching across four municipalities and covering an area comparable in size to the 23 wards of Tokyo, the wetland is a sanctuary for the iconic red-crowned crane (tancho) and a living museum of natural history protected under multiple international and national designations. Designated a Natural Monument in 1967 and registered in 1980 as Japan's very first Ramsar Convention site, Kushiro Wetland offers visitors a rare chance to witness an ecosystem that has remained largely unchanged since prehistoric times.

The Story of the Marshland: From Ancient Sea to Living Wetland

The story of Kushiro Wetland begins thousands of years ago, when the area now blanketed in reeds and sedges lay submerged beneath the Pacific Ocean. As sea levels gradually receded and a sandbar developed at the mouth of what is now the Kushiro River, the inland water became a brackish lagoon. Over the past three millennia, peat began to accumulate on the lake floor, slowly transforming the basin into the vast marshland we see today.

The Kushiro River winds its way through the heart of the wetland in dramatic meanders, joined by countless tributaries that branch like veins across the landscape. To the east, three remnant sea-trace lakes—Lake Toro, Lake Shirarutoro, and Lake Takkobu—remain as quiet witnesses to the marshland's oceanic origins. Throughout the wetland, small bottomless pools known as yachimanako (literally "valley eyes") puncture the peat layer, hidden beneath the grasses and a reminder that this seemingly flat terrain is far from passive ground.

For the indigenous Ainu people, the wetland was sacred territory. The red-crowned crane was known as Sarorun Kamuy, the "deity who dwells in the marsh," and its haunting calls echoed across landscapes that early Meiji-era settlers later dismissed as yachi—useless boggy land. It was precisely this perceived uselessness that, ironically, allowed the marshland to escape the wholesale agricultural conversion that consumed so many other wetlands in Japan.

Why Kushiro Wetland Earned Its Cultural Property Status

Kushiro Wetland was designated a Natural Monument under Japan's Cultural Properties Protection Law on July 6, 1967, with a protected area of approximately 5,012 hectares. The designation recognized the marshland as a "natural protection area" of exceptional scientific and ecological value. This protection followed earlier designations targeting the red-crowned crane: in 1935, an area of 2,700 hectares was first protected as the "Kushiro Crane Breeding Ground," and in 1952 it was elevated to Special Natural Monument status as "The Kushiro Cranes and Their Breeding Grounds."

The reasons for designation are layered. First, Kushiro Wetland represents the largest and most pristine example of low-altitude marshland landscape remaining in Japan—an ecosystem type that has all but disappeared from the rest of the country due to development. Second, it harbors an extraordinary concentration of biodiversity, including roughly 700 plant species and 1,300 animal species. Third, it serves as the principal habitat for the red-crowned crane, a bird that was once feared extinct in Japan until a small surviving flock was rediscovered here in the early 20th century. Finally, the wetland's geological structure—with its deep peat deposits, kettle ponds, and meandering rivers—offers a uniquely preserved record of post-glacial environmental change in northern Japan.

Following these national protections, Kushiro Wetland gained international recognition in 1980 as Japan's inaugural site under the Ramsar Convention on Wetlands of International Importance, and in 1987 the surrounding 28,788 hectares were designated as Kushiro Shitsugen National Park—the 28th national park in Japan.

Highlights and What to See

Around Kushiro Wetland

The wetland makes an excellent base for exploring eastern Hokkaido's other natural wonders. To the north lies Akan-Mashu National Park, home to the deep volcanic blue of Lake Mashu, the bubbling hot springs of Lake Akan, and a thriving Ainu cultural village. The port city of Kushiro itself is famous for its dawn-lit Nusamai Bridge, the lively Washo Fish Market where visitors can build their own seafood rice bowls, and Kushiro Fishermen's Wharf MOO. For visitors interested in conservation, the Kushiro Wetland Wildlife Conservation Center, operated by the Ministry of the Environment, offers exhibits on rare species such as Blakiston's fish owl and rehabilitative care for injured wildlife.