Underwater gas release and dispersion characteristics are important to assess and manage potential risks. This paper presents an experimental and numerical investigation of underwater gas release and dispersion behavior. A small-scale experimental setup is designed and developed for underwater gas release and dispersion study. A series of release scenarios are carried out to study the effect of release size, leak pressure, and leak direction on dispersion behavior. The underwater gas dispersion behavior is analyzed flour the risk assessment perspective. The considered parameters included plume offset, plume radius and fountain height for different scenarios. The experimental results are used to test and verify numerical computational fluid dynamics model using Eulerian-Lagrangian approach. The developed numerical model is subsequently used to analyze the gas plume in a full-scale scenario. The developed model would help to support risk assessment and response planning of potential subsea gas release accidents.