A method for governing the elevation, attitude and structural integrity of a pressure-containing vessel in a body of liquid counterbalances flotation and incompressible ballast mediums against each other in separate serial compartments. Varying the quantity of incompressible ballast medium allows control of the elevation and attitude of the vessel. If the flotation medium is compressible, varying the quantity of flotation medium allows control of the ambient pressure of the vessel. The method facilitates floating and towing and laying of an undersea pipeline on, to and at a deep water site.

A method for governing the elevation, attitude and structural integrity of a pressure-containing vessel in a body of liquid counterbalances flotation and incompressible ballast mediums against each other in separate serial compartments. Varying the quantity of incompressible ballast medium allows control of the elevation and attitude of the vessel. If the flotation medium is compressible, varying the quantity of flotation medium allows control of the ambient pressure of the vessel. The method facilitates floating and towing and laying of an undersea pipeline on, to and at a deep water site.

A method for governing the elevation, attitude and structural integrity of a pressure-containing vessel in a body of liquid counterbalances flotation and incompressible ballast mediums against each other in separate serial compartments. Varying the quantity of incompressible ballast medium allows control of the elevation and attitude of the vessel. If the flotation medium is compressible, varying the quantity of flotation medium allows control of the ambient pressure of the vessel. The method facilitates floating and towing and laying of an undersea pipeline on, to and at a deep water site.

A method for governing the elevation, attitude and structural integrity of a pressure-containing vessel in a body of liquid counterbalances flotation and incompressible ballast mediums against each other in separate serial compartments. Varying the quantity of incompressible ballast medium allows control of the elevation and attitude of the vessel. If the flotation medium is compressible, varying the quantity of flotation medium allows control of the ambient pressure of the vessel. The method facilitates floating and towing and laying of an undersea pipeline on, to and at a deep water site.

A method for governing the elevation, attitude and structural integrity of a pressure-containing vessel in a body of liquid counterbalances flotation and incompressible ballast mediums against each other in separate serial compartments. Varying the quantity of incompressible ballast medium allows control of the elevation and attitude of the vessel. If the flotation medium is compressible, varying the quantity of flotation medium allows control of the ambient pressure of the vessel. The method facilitates floating and towing and laying of an undersea pipeline on, to and at a deep water site.

A method for governing the elevation, attitude and structural integrity of a pressure-containing vessel in a body of liquid counterbalances flotation and incompressible ballast mediums against each other in separate serial compartments. Varying the quantity of incompressible ballast medium allows control of the elevation and attitude of the vessel. If the flotation medium is compressible, varying the quantity of flotation medium allows control of the ambient pressure of the vessel. The method facilitates floating and towing and laying of an undersea pipeline on, to and at a deep water site.

A subsea system for installing, suspending and removing underwater equipment below the surface of the sea is provided. The subsea system includes a landing base module for landing and positioning underwater equipment thereupon, the landing base module comprising a base member and a first buoyancy system; and a second buoyancy system for affixing to the underwater equipment, the second buoyancy system having sufficient buoyancy to float the underwater equipment toward the surface of the sea when detached from the landing base module, wherein the underwater equipment includes a ballast system structured and arranged to permit the underwater equipment to be lowered onto the landing base module. A method for installing, suspending and removing underwater equipment below the surface of the sea and a kit of parts are also provided.