Holothuria (Semperothuria) cinerascens is a species of sea cucumber in the family Holothuriidae.

The ashy sea cucumber appears as a black tube with grey or red specs giving it the overall appearance like ashes and varies in size from ten to thirty centimeters.

This species can be found around coral reefs and rocks, in tide pools, in deeper waters, lagoons, and bays, often hiding in very tight spaces.

Their movement and migration patterns depend on their depth of sea level they are located at, influence of light intensity, the temperature conditions and the amount of predators surrounding the area.

As for cultural connections (Moʻolelo), these sea cucumbers were eaten and used as medicine during traditional Hawaiian life.