The Kasei Valles are a giant system of canyons in Mare Acidalium and Lunae Palus quadrangles on Mars, centered at 24.6° north latitude and 65.0° west longitude.

It runs initially northward, then turns eastward and appears to empty into Chryse Planitia, not far from where Viking 1 landed.

[citation needed] These branches recombine at around 63° west longitude, forming a large island between the channels known as Sacra Mensa.

[4] Three sets of enormous cataracts (dry falls) are present in the area between an "island" feature in the southern channel, Lunae Mensae, and the crater Sharonov.

[5][6] These cataracts, evidently carved during megaflooding events, have headwalls up to 400 m high[6] and are considerably larger than the largest terrestrial analog, Dry Falls.