open sea—
1. the part of the sea not closed in by land (not a bay or harbor):
- A “black south-easter,” the wind most feared on this coast, forced most of the fleet to run for open sea.
2. the part of the sea outside the territorial jurisdiction of any country:
- The real place of meeting between the Englishman and the Spaniard was on the open sea.
3. sea that is practically free from ice and navigable:
- It is probable that an open sea stretches to the Antarctic pole.
open water — = open sea 3:
- Von Wrangell found open water—or what is now often called a “Polynia,” an open sea.