Related Clues:

• Deep hole
• The Grand Canyon is a grand one
• Colorado creation
•  Chasm
• It's beyond deep
• Ravine formed by a river
• Narrow, steep-sided valley
• Grand attraction
• Wide difference
• Unfathomable cavity, e.g.
• Large gully
• Deep valley
• Vast pit
• Lowest depth
• Hardly a miniature gulf