The three-ribbed kelp is a light yellowish-brown color. They are about 25 cm to 4 m long and 18 cm wide. They have three groves that run down the middle of them. They attach to rocks.

They can be found in the Bering sea, Aleutian Islands, Alaska, to northern Washington, Kurile Islands and Russia.

The three ribbed kelp can live slightly below and slightly above low tide.