A deepwater pipeline is towed to a predetermined position by a bottom
towing method with a leading end of the pipeline attached to a towing
vessel and the trailing end of the pipeline attached to a trailing
vessel. The trailing end is supported near the seabed using the trailing
vessel, while the pipeline is dragged along the seabed. A towing speed is
established, and a hang off angle for the leading end is maintained by
raising and lowering the trailing end to control the length of the
pipeline dragged along the seabed, and thus the amount of drag applied by
the seabed to the pipeline. In a method for bottom towing and submerged
flying of a riser having a leading end and a trailing end, the riser is
towed by the bottom towing method at a first speed until the trailing end
of the riser lifts off the seabed, whereupon the towing speed is
increased.