Nerita undata is a species of sea snail.
The shell can grow up to 4 cm, with radial ridges on the shell surface; columella with three teeth. Pale in colour with variable darker markings, sometimes uniformly bluish-black, pale interior. Habitat: littoral fringe rocks.
Indo-West Pacific: northeastern South Africa to Kenya, ranging through central region, including Indonesia and the Philippines, to Melanesia and Micronesia, southern Japan to northern Australia.