An old mill is a type of amusement park ride where unaccompanied boats float on guideways and traverse through dark tunnels. These themed dark rides originated in the late 19th century and are known by a variety of names, including tunnel of love and river cave. While generally considered a gentle ride, a variation of an old mill featuring a climactic splashdown ending, similar to the modern-day log flume, is known as a mill chute.

A dark ride or ghost train is an indoor amusement ride on which passengers aboard guided vehicles travel through specially lit scenes that typically contain animation, sound, music and special effects. Appearing as early as the 19th century, such exhibits include tunnels of love, scary themes and interactive stories. Dark rides are intended to tell stories with thematic elements that immerse riders, which unfold throughout course of the attraction.