Drowning is death caused by asphyxia due to the aspiration of fluids into the airways or lungs, resulting in airway obstruction within 24 hours. One of the examinations to establish the diagnosis of drowning victims is a laboratory examination of diatom identification. This research aims to know the morphological description and types of diatoms that live along the Upper, Middle, and Lower Ciliwung Watersheds, to facilitate the identification of drowning victims found in the Ciliwung River. The research design is qualitative descriptive. The data in this study were the results of observations and analysis of Ciliwung river water samples at the Research Laboratory of the Faculty of Medicine, Indonesian Christian University. The study's results found 17 different species at the Katulampa Dam, 19 at the Ciliwung Bridge, and 14 at the Manggarai Sluice Gate. From a total of 22 species of diatoms found, overall, the widest distribution was Nitzschia sp, Navicula sp, Fragilaria sp, and Cyclotella sp. The distribution and types of diatoms found are closely related to current velocity and water discharge, temperature, and river turbidity.