In the extended edition of Fellowship of the Ring Gandalf fights the Balrog and then falls for about 70 seconds.

It takes about 12 seconds to reach terminal velocity: 0.5 * g * t^2 = 0.5 * 9.81 * 12^2 ~ 706m

The remaining 58 seconds Gandalf is at terminal velocity (not speeding up) of 53m/s which is v * t = 53 * 58 ~ 3074m. For a total of 3780 meters, or about 2.35 miles.

Pretty impressive free-fall considering they were ALREADY under ground.