With　the　demand　for　lower　carbon　emissions　and　the　increasing　use　of　clean　energy　instead　of　traditional　fossil　fuels,　offshore　production　of　liquefied　natural　gas　(LNG)　has　become　a　major　mode　of　energy　transportation　and　storage.　Due　to　its　cryogenic　characteristics,　LNG　produces　special　physical　phenomena　once　it　leaks　from　cargo　ships　or　offshore　pipelines.　To　investigate　the　mechanical　behavior　and　thermal　interaction　between　the　jetreleased　LNG　and　surrounding　ambient　water,　a　set　of　laboratory　experiments　with　various　measurements　was　designed　and　developed　to　perform　controllable　cryogenic　liquid　horizontal　release　under　water.　The　hydrodynamic　phenomenon　of　flow　behavior,　effect　of　release　dynamics,　and　instability　mechanism　of　the　breakup　process　caused　by　the　formation　of　vapor　bubbles　were　observed　and　quantified　under　different　orifice　sizes　and　release　pressures.　In　addition,　a　four-stage　physical　model,　established　by　Raj,　that　described　the　breakup　dynamics　transition　from　jet　liquid　to　diffusion　plume　was　validated　and　recorded　using　a　visualized　high-speed　video　camera.　Two　commonly　used　mathematical　methods,　the　Rosin-Rammler　distribution　and　lognormal　distribution,　were　used　to　quantify　and　evaluate　the　average　bubble　sizes　in　1.95　+/-　0.06　mm,　2.18　+/-　0.06　mm,　and　2.2　+/-　0.1　mm　from　1,　3-5　mm,　using　image　processing　techniques.　The　bubble　breakup　mechanisms　and　empirical　equations　were　developed　and　discussed　with　a　complete　set　of　literature　data　based　on　a　nondimensional　analysis　of　various　release　conditions,　which　was　validated　with　droplet　size　data　obtained　from　laboratory　studies　in　both　gas　and　liquid　co-flowing　jets.　The　-0.38　power-law　scaling　relationship　between　the　dimensionless　length　scale　of　d/lm　and　the　mixture　Weber　number　was　established　to　predict　the　breakup　of　the　vapor　bubble　size　from　subsea　release　fluids.