Indonesian marine natural products are diverse, reflecting biodiversity of genes, species, and environment. Through evolution, marine natural products (MNPs) are biosynthesized via multiple enzymatic cascade reactions that can carry out specific biological functions within and/or between organisms. Accordingly, MNP structures can be biologically prevalidated that can be used for drugs, chemical probes, and scientific developments. Skeletons, building blocks, or scaffolds are either conserved or evolved within marine organisms as response to their environment. Although the chemical diversity and significant biological activity can be evaluated, there are possible limitations of the detection methods because of the existence of reactive MNPs. Since 1972, 911 molecules including 879 original MNPs, 4 structures isolated for the first time but known as synthetic entities, 33 structural revisions, 34 artifacts, and 1 proposed MNPs have been discovered. The Indonesian MNPs are approximately sourced from 108 species, 116 genera, 76 families, 37 orders, 17 classes, 12 phyla, and 5 kingdoms. Of the 911 molecules, only 37 MNPs are categorized to have potent biological activities. The chapter covers the structures of organic molecules (original and revised), potent biological activities, their structure determination studies, and supply challenge of talented MNPs from Indonesia.