The potential use of aquatic organisms such as macroinvertebrates and algae in the estimation of postmortem submersion interval (PMSI – defined as the time from when a body is submerged to the point of discovery by authorities) has received increased attention. To date, the majority of forensic studies dealing with corpses/carrion have been concentrated on terrestrial environments compared to aquatic ecosystems. Additionally, those studies pertaining to corpses in aquatic systems were primarily focused on terrestrial insects colonizing the corpses as they bloat and rise to the surface. With a few possible exceptions, no true aquatic insects have evolved to feed exclusively on decomposing carrion. Therein lies the primary problem in aquatic environments in that there are no purely sarcophagous insects to compare with the common terrestrial indicator species such as blow flies (Calliphoridae). A brief overview on the current research on aquatic organisms and their role in determining a PMSI, important case studies utilizing aquatic insects to solve crimes and future research directions involving aquatic insects and algae will be discussed.