Thecacera pacifica is a species of sea slug, a nudibranch, a marine gastropod mollusk in the family Polyceridae.

[2] This species is known from the African coast of the Indian Ocean (Mozambique) to Indonesia and Vanuatu.

[3] This polycerid nudibranch is translucent orange in colour with black tips to the rhinophores and gills.

The rhinophore sheaths are edged with black with a patch of blue at the widest part.

Some specimens have black linear marks on the body with blue centres.