General:
* Profound: (especially for thoughts, feelings, or meaning)
* Intense: (strong and powerful)
* Significant: (important and meaningful)
* Substantial: (large in amount or importance)
* Abysmal: (extremely deep, often used figuratively for something very bad)
Physical Depth:
* Abyssal: (extremely deep, referring to the ocean depths)
* Bottommost: (at the very bottom)
* Low-lying: (situated at a low level)
* Unfathomable: (too deep to be measured or understood)
Figurative Depth:
* Intimate: (closely connected)
* Meaningful: (having a significant meaning)
* Thought-provoking: (stimulating thought)
* Enigmatic: (mysterious and difficult to understand)
Other Related Words:
* Extensive: (covering a wide area)
* Comprehensive: (including everything)
* Thorough: (done carefully and completely)
The best word to use will depend on the specific context and the nuance you want to convey.