Okenia mediterranea is a species of sea slug, specifically a dorid nudibranch, a marine gastropod mollusc in the family Goniodorididae.

[2] This Okenia has a broad body and nine pairs of lateral papillae.

There is a ridge of short, partly fused papillae down the midline in front of the gills and a row of three short papillae or tubercles on either side of this ridge.

The body is translucent white and the papillae and gills are yellow, spotted with orange.

[2] The diet of this species is the ctenostome bryozoan Alcyonidium cf.