A method of assembling a pipeline at a seabed location comprises landing a connection tool on the seabed over a free end portion of a first pipeline section already placed on the seabed. The connection tool is locked to the free end portion of the first pipeline section, a lower end of a second pipeline section is connected to the connection tool via an initiation line. While applying tension to the initiation line against reaction force of the connection tool, at least a lower end portion of the second pipeline section is landed on the seabed with the lower end facing a free end of the first pipeline section. The lower end of the second pipeline section is then pulled into mechanical engagement with the free end of the first pipeline section.