Abstract: The invention relates to a method and an arrangement for shipping a reel (1) onboard a ship (2) where the reel (1) is at least partly placed into a cargo space (3) of the ship. The arrangement comprises a reel holder (4), which holds the reel (1) placed therein substantially in position at least in the horizontal and downward direction, and the reel holder (4) is arranged onto a tweendeck (5) in the ship's cargo space (3) that is placed at a distance from the bottom (6) of the ship's cargo space, closer to the metacentre of the ship (2) than to the bottom (6) of the ship. The invention also relates to a tweendeck to be used as a transport support for the reel (1) in sea transport and to a tweendeck arrangement in the ship's cargo space (3).