Riser-less managed pressure operations

A method of conducting a managed pressure operation from a water-based rig, the method comprising:

• assembling a subsea assembly comprising a first pressure control device and a connector, the first pressure control device including an outer housing, and an annular seal configured to seal off an annulus formed between the outer housing and a tubular string extending through the outer housing, in which the assembling further comprises connecting a longitudinally extendable and compressible slip joint in the subsea assembly between the first pressure control device and the connector;
• lowering the subsea assembly through water from the rig to a subsea wellhead installation;
• connecting the connector of the subsea assembly to the subsea wellhead installation;
• and
• positioning the tubular string in an internal flow passage extending through the subsea assembly, whereby the annular seal seals against an external surface of the tubular string, the tubular string being exposed to the water between the rig and the subsea assembly.