An exclusive economic zone is an area of the sea in which a coastal state claims the sovereign rights to conduct economic activities (including exploration and exploitation of natural resources) and the jurisdiction over marine scientific research, the protection and preservation of the marine environment, and other matters. The United Nations Convention on the Law of the Sea (UNCLOS) defines that it shall not extend beyond 200 nautical miles (about 370 km) from the baselines from which the breadth of the territorial sea is measured (the line that borders land and water surfaces when the sea level is at its lowest).
Countries with exclusive economic zones have the right to investigate, develop, and preserve various resources (organisms, minerals, etc.) within them. At the same time, they also have an obligation to manage these resources and environments properly.
Japan's land area is roughly 380,000 km2, but the combined area of its territorial sea and EEZs is some 4.47 million km2, which is about 12 times the size of the land and the sixth largest in the world.
For this country—surrounded by sea with small land area—EEZs and other waters are indispensable places where it's permitted to exclusively develop valuable marine energy and mineral resources and exploit aquatic resources.
Tokyo has a vast EEZ, extending from the inner Tokyo Bay to the Izu and Ogasawara Islands. Its area is approximately 1.7 million km2, about 40% of the nation's entire EEZs.
This illustrated diagram is provided for convenience and includes geographic intermediate lines in waters where the borders between foreign countries haven't been defined.
* Waters as defined in Article 2, Item (ii) of the Act on Exclusive Economic Zone and Continental Shelf
| Land area | Approx. 380,000 km2 |
| Territorial sea (including internal waters) | Approx. 430,000 km2 |
| Exclusive economic zone (including contiguous zone) | Approx. 4.05 million km2 |
| Territorial sea (including internal waters)＋ Exclusive economic zone (including contiguous zone) |
Approx. 4.47 million km2 |
Chart Source: Japan Coast Guard website, "Illustrated Diagram of Japan's Territorial Sea, Etc."
(https://www1.kaiho.mlit.go.jp/JODC/ryokai/ryokai_setsuzoku.html)
* All provisions of UNCLOS Part VII (High Seas) apply to the solid lines.
Certain matters, including freedom of navigation, also apply to the dotted lines.
Chart Source: Ditto, "Terms of Territorial Sea, Etc."
(https://www1.kaiho.mlit.go.jp/JODC/ryokai/zyoho/msk_idx.html)
The official website of the Tokyo Metropolitan Government