seven seas

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun plural All the oceans of the world.

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

• noun informal All of the oceans of the world. (North and South Atlantic, North and South Pacific, Indian, Arctic and Antarctic)

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun an informal expression for all of the oceans of the world