Aquatic biodiversity is a fundamental component of aquatic environments and ecosystems. Hence, its study is essential for conservation and management of such environments. This module aims to enhance students’ knowledge and familiarity of tropical aquatic biodiversity through directed studies led by experts in freshwater and marine organisms. Biota in Singapore, in particular, will be highlighted. Emphasis will be on organismal diversity as well as taxonomy and classification, on top of a range of other topics such as structure and function, ecology, conservation, and economic importance to be covered within the context of selected organismal groups. Learning outcomes include appreciation of the importance of aquatic biodiversity as well as knowledge, familiarity, and understanding of selected groups of aquatic biodiversity.