A variety of factors are apt to determine marine productivity; the most crucial of which is food supply in the marine environment. Diatoms, which belong to phytoplankton flora, may represent a food supply for sand sea cucumbers (Holothuria scabra) through deposit-feeding. Sand sea cucumber is one of the classes in the Echinodermata phylum, known for its soft-textured, fleshy, flat cylindrical body. Being continuously utilized, sand sea cucumbers possess a high economic value. However, over-usage may cause a decrease in its population. To overcome this problem, pen culture cultivation has proved its efficacy to guarantee a dominant sea cucumber flow of stocks. Sand sea cucumbers feed on naturally available elements in the cultivation process. Thus, this research was designed to investigate the utilization of benthic diatoms as food for sand sea cucumbers cultivated through pen culture. Observation of 70 sand sea cucumbers cultivated in 3 m x 3 m size of pen culture was assessed. Seagrass leaves (Enhalus acroides) were planted in pen culture, as the habitat of benthic diatoms, whereas chicken feces represented the catalyst. Upon examinations, benthic diatoms were detected in almost 83% of sand sea cucumbers. Therefore, it is recommended to use benthic diatoms as a food supply for sand sea cucumber in cultivation purposes.