For a whore is a deep ditch - See on Proverbs 22:14 (note).

For a whore is a deep ditch,.... Or, "as a deep ditch", so Aben Ezra; to which she may be compared for the filthiness of her whoredoms, and for her insatiable lust, as well as for her being never satisfied with what she receives from her lovers. Plautus compares (g) her to the sea, which devours whatever you give, and yet nothing appears; and another (h) calls a whore Charybdis, from her swallowing up and devouring all a man has. She is as a ditch that has no bottom, into which those that fall are ever sinking deeper and deeper, till they get into the bottomless pit; for there is seldom any recovery from this dreadful evil;
and a strange woman is a narrow pit; or "well" (i); into which when men fall, they bruise themselves in a terrible manner, by beating from side to side; and out of which they cannot extricate themselves; at least not easily, but with great difficulty, if ever. This may very well be applied to the whore of Rome, and the filthiness of her fornications; and the dreadful state of those who are drawn in to commit fornication with her.
(g) Truculaetus, Acts. 2. Sc. 7. v. 16, 17. "Lucuculetum coenum", Bacchides, Acts. 3. Sc. 1. v. 11. "Lutea meretrix", Trucul. Acts. 4. Sc. 4. v. 1l. (h) Sydonius Apollinar. l. 9. Ep. 6. (i) "putens", V. L. Pagninus, Montanus, Junius & Tremellius, Piscator, Michaelis, Schultens.

deep ditch--a narrow pit, out of which it is hard to climb.
lieth in wait--to ensnare men into the pit, as hunters entrap game (compare Proverbs 22:14).