open sea

IPA/ˈəʊpən sˈiː/
IPA/ˈoʊpən sˈiː/

open sea — noun

1. the main part of the sea beyond narrow channels, bays, or waters close to land

1.名詞C1
釋義

the main part of the sea beyond narrow channels, bays, or waters close to land

例句

After leaving the harbour, the fishing boat headed for the open sea.

head for the open sea after leaving shore

By noon, the storm had pushed the small yacht into the open sea.

into the open sea after a change in position

同義詞
  • open water

    broader; can mean any clear stretch of water, not only the sea

  • the high seas

    more formal and often legal or nautical in tone

  • offshore waters

    focuses on sea areas away from the immediate coast

反義詞

文法句型

the open sea

out on the open sea

head for the open sea

return from the open sea

用法筆記

Usually contrasts with the coast, a harbour, or a narrow passage. It often appears with movement verbs such as 'head for', 'cross', or 'sail onto' when a boat leaves sheltered water.

常見錯誤

❌The boat went to open sea after breakfast.
✅The boat went to the open sea after breakfast.
💡this sense usually takes 'the'.
❌The children swam in open sea by the beach.
✅The children swam in the open sea away from the beach.
💡the phrase suggests water beyond the sheltered coastal area, not the shallow edge by the shore.

2. sea that lies beyond the area officially controlled by any country

2.名詞C2
釋義

sea that lies beyond the area officially controlled by any country

例句

The treaty sets rules for ships operating on the open sea.

operate on the open sea in legal discussion

Pirates attacked the tanker once it reached the open sea.

reach the open sea outside national control

同義詞
反義詞

文法句型

on the open sea

rights on the open sea

operate on the open sea

the law of the open sea

用法筆記

Used mainly in legal, political, or maritime-policy writing. Distinguish from sense 1: this sense is about jurisdiction, not simply being far from the coast.

常見錯誤

❌The ferry entered open sea after leaving the port, so it was outside every country's law.
✅The ferry entered the open sea after leaving the port.
💡leaving port does not automatically mean the ship is beyond national waters.
❌The beach is on the open sea.
✅The beach faces the open sea.
💡this sense refers to the sea area itself, not land beside it.