Kasai Marine Park

In short

Kasai Marine Park is located off the coast of Kasai facing Tokyo Bay, comprising two artificial beaches and an offshore marine area extending about 2 kilometers. It is connected to the landside Kasai Rinkai Park by Kasai Nagisa Bridge. In October 2018 (Heisei 30), it became the first wetland in Tokyo to be registered under the Ramsar Convention.

• ​Nishi-nagisa (West Beach)​​: A wide sandy beach located just across Kasai Nagisa Bridge. Along with strolls, visitors enjoy clam digging on the tidal flats at low tide from spring through early summer.
• ​Higashi-nagisa (East Beach)​​: A wild bird sanctuary where entry by people is prohibited in principle. The mudflats are home to the amphibious mudskipper, for which Tokyo Bay marks the northern limit of its habitat.
• ​Winter Migratory Birds​​: In winter, flocks of greater scaup gather in such numbers that they seem to cover the sea, and great crested grebes are also frequently seen.

History and Highlights

​Kasai Marine Park​ is located off the shore of Kasai in Edogawa City. It consists of two artificial beaches—Nishi-nagisa and Higashi-nagisa—and an offshore sea area extending about 2 kilometers. The park covers an area of approximately 412 hectares, most of which is water. The majority of the site is a tidal flat spreading across the estuaries of the Arakawa River and the Kyu-Edogawa River, known as Sanmaisu.

Historically, this area was a fishing ground where nori seaweed, asari clams, and hamaguri clams were harvested. It was also a leisure destination offering clam digging in spring, sea bathing in summer, goby fishing in autumn, and recreational boating in winter.

During Japan's era of rapid economic growth, pollution problems such as deteriorating water quality and ground subsidence arose, while land reclamation also progressed. A group called "Edomae no Haze o Mamoru Kai" (Association to Protect Edo-style Goby) gathered one million signatures to petition for the preservation of Kasai's offshore waters. In its 1970 (Showa 45) development plan, the Tokyo Metropolitan Government decided to preserve these tidal flats, which were the last remaining natural shorelines in Tokyo. The park opened in June 1989 (Heisei 1).

On October 18, 2018 (Heisei 30), it was registered as Tokyo's first Ramsar wetland.

Sights and Experiences

• ​Sandy Beach of Nishi-nagisa​​: A broad sandy beach opening directly to Tokyo Bay. From afar, Mount Fuji and the Tokyo Gate Bridge can be seen, while Tokyo Disney Resort can be viewed nearby. From spring to early summer, visitors can harvest shellfish such as asari and hamaguri clams on the flats at low tide. However, there are restrictions on equipment and the amount collected. Swimming is offered as an activity in summer, during which swimming is permitted in designated areas. Swimming is not allowed during other periods.
• ​Higashi-nagisa​​: A wild bird sanctuary where entry is prohibited in principle. It features a lush reed bed used by many geese and ducks, as well as sandpipers and plovers. The mudflats are home to the mudskipper, for which Tokyo Bay is the northern limit of its habitat.
• ​Seasonal Birds​​: In winter, greater scaup gather in dense flocks as if covering the sea, and many great crested grebes are seen. On the sandy beach of Nishi-nagisa, nesting little terns can be observed every year.

Tips for Visitors

The park is an 11-minute walk from Kasai-Rinkai-koen Station on the JR Keiyo Line. Crossing Kasai Nagisa Bridge—designed in the image of a yacht's mast—from the landside Kasai Rinkai Park leads directly to Nishi-nagisa. Bicycles are not permitted inside the park.

The seascape changes significantly with the ebb and flow of the tide. If you wish to walk on the tidal flats, plan your visit according to low tide times. Park opening hours are extended depending on the season, so it is advisable to check the closing time beforehand.

The mudskippers of the tidal flats are also introduced in the "Seas of Tokyo" area at Tokyo Sea Life Park. Wild birds can also be observed at the Bird Sanctuary in Kasai Rinkai Park.