flume

A ravine or gorge, usually one with water running through.

Near the upper end of the portage the river falls 100 feet in as many rods, the water going at lightning speed through a natural flume in the rock. So rapid is the descent that the water in the flume is but 3 feet deep. We named this the "Devil's Slide."

An open channel or trough used to direct or divert liquids, especially to carry materials (logs, mined material, etc) or people (as a water slide), especially (but not always) one where the walls are raised above the surrounding terrain rat

[...] the flumes are generally not dark rides and they run much faster. Two notable exceptions are the Timber Mountain[…]

[…] aqueducts, wooden half-barrels laid on their sides and elevated on rusty trestles, to rush the icy spring water down the mountainside to the fields. This system of irrigation through flumes was simple, but effective. There were miles of flumes and, […] the children of the island used the flumes as water slides. The location of certain especially fast and dangerous flumes was kept secret in families for generations and passed on in unquestioned solemnity . It was against the law to use the flumes as water slides[…]

To transport (logs of wood) by floating them along a water-filled channel or trough.