Excursion Funnel

The Excursion Funnel is a game mechanic introduced in Portal 2. The mechanism creates a funnel of liquid asbestos that the player may enter or exit at any time. It seems to defy the laws of gravity, allowing any who enter to become weightless and travel along the path of the Funnel. Anyone or anything caught inside the Funnel travels in the direction that the Funnel is flowing, unless the Funnel is made to reverse, which is usually accomplished through the activation of a button.

Excursion Funnels can pass through portals and can cross vast distances, and can therefore can be used to solve puzzles in which Funnels may not initially appear to be useful. If an Excursion Funnel is reversed, then it is possible for objects to use the portals through which the Funnel is acting.

Excursion Funnels can also act as a mode of transportation for the player or objects across large gaps, as well as Gels. Gels caught in the Excursion Funnel will slowly follow the direction of the Funnel until the substance collides with a wall or until the Funnel suddenly disappears, making funnels useful for coating large areas in a short amount of time.

Trivia
When inside an Excursion Funnel in the single player campaign, soothing music plays.