The introduction of a specialised passage regime for archipelagic sea-lanes was one of the most innovative features to the 1982 Law of the Sea Convention. Article 53(9) of the Convention requires an archipelagic state to refer any proposals for the designation or substitution of sea-lanes or the prescription of traffic separation schemes to the "competent international organisation" with a view to their adoption. In May 1996 at the 67th session of the Marine Safety Committee of the International Maritime Organisation (IMO), the Republic of Indonesia submitted a proposal for the adoption of various sea-lanes and air routes through and over its archipelagic waters. This was the first proposal of its kind. This article traces the progress of this proposal through the IMO procedures and draws some conclusions about the wider significance of this new role for the IMO.