Abstract: A subsea packer system for large diameter casings where an inflatable liner is connected in a string of casing and has an inner tubular drillable insert member with a longitudinal bypass passage. A string of tubing with a releasable running tool is connected to a casing well head on the casing for transport into a well bore and has an isolation seal member for closing off inflation ports which extend through the insert member to the inflatable packer. The bore of the insert member is sized to a bore diameter less than the bore diameter of the casing well head and is less than the diameter of the casing.