open water

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun An expanse of an ocean, sea, or large lake which is distant from shore and devoid of nearby islands or other obstructions.
• noun In a river, pond, or other small body of water, an area of surface unobstructed by aquatic vegetation, boulders, and the like, adequate for navigation or swimming.
• noun An area of an ocean, sea, lake, or river which is not covered by ice.