領海（りょうかい、ryoukai）
- territorial waters

The Japanese word 領海領海, pronounced りょうかい, refers to a nation's territorial waters. It encompasses the area of the sea that a country claims as its own, extending from its coastline out to a certain distance. This area is subject to the country's laws and regulations, similar to its land territory. Specifically, 領海領海 includes the waters, the seabed, and the airspace above them. It is crucial for national security, resource management, and international relations.

⚫︎日本は 領海 の安全を確保するために巡視船を配備しています。 Translation: Japan deploys patrol ships to secure its territorial waters. ⚫︎漁船が 領海 内で違法操業を行っていることが確認されました。 Translation: It was confirmed that fishing boats were illegally operating within territorial waters. ⚫︎その島は 領海 の境界線上に位置しています。 Translation: That island is located on the boundary of the territorial waters.

You use 領海領海 when discussing matters related to a country's territorial waters. It is used in contexts such as: ⚫︎Describing maritime borders. ⚫︎Discussing fishing rights. ⚫︎Talking about national security in relation to the sea. ⚫︎Referring to international law related to maritime boundaries. It is a formal term, often used in official documents, news reports, and discussions about legal and political topics.

⚫︎The word is written in kanji as 領海領海. ⚫︎The reading (furigana) is りょうかい. ⚫︎There is no other common way to write this word. ⚫︎There are no variations in the okurigana.

There are no direct synonyms for 領海領海 that carry the exact same meaning. However, you might use phrases or related terms depending on the context: ⚫︎領土 - Territorial territory (This includes land territory in addition to maritime). ⚫︎排他的経済水域 - Exclusive Economic Zone (EEZ) (This is the area beyond the 領海領海 where a nation has certain rights regarding resources.)

There aren't really antonyms as such, but consider related concepts or areas outside of a nation's control: ⚫︎公海 - High Seas (This is the open ocean outside of any nation's jurisdiction.)

日本は 領海 内の安全保障を強化するため、新しい哨戒機を導入しました。 ・Translation: Japan introduced a new patrol aircraft to strengthen its security within its territorial waters. ・Explanation: This sentence explains that Japan is improving its security in the area of the sea it claims as its own.

領海侵犯は国際法違反にあたります。 ・Translation: Violation of territorial waters is a violation of international law. ・Explanation: This sentence clarifies that entering another country's territorial waters without permission is against international law.

The word 領海領海 is composed of two kanji: 領 (ryō), meaning "territory" or "domain," and 海 (kai), meaning "sea" or "ocean." Therefore, 領海領海 literally means "territorial sea" or "territorial waters."