MIKE 21 is a computer software tool used for simulating and modeling water bodies, such as rivers, lakes, and coastal areas. It helps researchers and engineers analyze various hydrodynamic processes, including water flow, sediment transport, and pollutant dispersion. The software is widely utilized in environmental studies, urban planning, and flood risk management. By providing detailed visualizations and predictions, MIKE 21 supports decision-making for sustainable water resource management and infrastructure development.