Mines and minefields are designed to be hidden dangers:
… but who knows what minefields lay
(example of usage from ‘The Would-Be Daddy’ By Jacqueline Diamond via ‘Google Books)
With your natural/man-made comment/distinction in mind, quicksand is another hidden danger and like reefs, it usually occurs naturally and although potentially deadly, harbors no ill will towards those who unknowingly happen upon it.
(description of quicksand as being a hidden danger found in ‘Reading Minds: The Study of English in the Age of Cognitive Science’ by Mark Turner, via ‘Google Books’)
Although it could be used in an unanswerable question with “await/s,” similar to your colleague’s expression:
… but who knows if [patches of] quicksand
... it would probably be more idiomatic if used in a declaration with “abounds”:
… but [as we all know] quicksand
[in this industry].
(example usage of “quicksand awaits” from ‘America's Unwritten Constitution: The Precedents and Principles We Live By’ by Akhil Reed Amar, via ‘Google Books’
and of “quicksand abounds” from ‘Katyń: The Untold Story of Stalin's Polish Massacre’ by Allen Paul, also via ‘Google Books’)
(It’s interesting to note that the short passage by Mr. Paul found at the last link contains not only my suggestion of “quicksand abounds,” but also two other options that are (or closely resemble) two other answers, both very good, imo)