The word(s) "tunnel" appears 2 time(s) in 2 verse(s) in Quran in Abdullah Yusuf Ali translation.

(1) If their spurning is hard on thy mind, yet if thou wert able to seek a tunnel in the ground or a ladder to the skies and bring them a sign,- (what good?). If it were Allah's will, He could gather them together unto true guidance: so be not thou amongst those who are swayed by ignorance (and impatience)!

(2) But when they reached the Junction, they forgot (about) their Fish, which took its course through the sea (straight) as in a tunnel.