low tide

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

• noun The lowest level of the tide.
• noun The time at which the tide is lowest.

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

• noun The tide at its lowest level for a particular tidal cycle at a certain place.
• noun The time of day when the sea has receded to its lowest level.

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

• noun the lowest (farthest) ebb of the tide