The Cook's Petrels are seabirds usually remain in open waters. They are found in the Pacific Ocean from New Zealand north to the Aleutian Islands. They may be seen well off the west coast of the United States and the west coast of tropical South America.
They measuer about 25 - 30 cm in length and have a wingspan of 65 - 66 cm. They are pale below and mottled dark on the upper plumage.