quicksand

nouns

a treacherous situation that tends to entrap and destroy
quicksand
is a type of (narrower)
a complex or critical or unusual difficulty
"the dangerous situation developed suddenly"; "that's quite a situation"; "no human situation is simple"
situation
a pit filled with loose wet sand into which objects are sucked down
quicksand
is a type of (narrower)
a sizeable hole (usually in the ground)
"they dug a pit to bury the body"
cavity, pit