Padina sanctae-crucis is a species of brown macroalgae in the family Dictyotaceae. It is a tropical brown algae species native to the south pacific that belongs to the Padina genus. this alga includes sexual reproduction and spore-producing asexual reproduction which is moved with the tide until spores plants itself on a hard rocky substrate. Other habitats include rocks and shell fragments in the shallow sublittoral, seagrass meadows, mangrove roots and coral reefs on tidal flats.