The author discusses in detail the project o f the new convention for cargo transport wholly or in part by sea. The UNCITRAL Working Group for Transport has been dealing with this matter since 2002, and has now finished its work. This paper is the first o f its kind in Polish legal literature. The future convention is to constitute the basis for regulation within the convention of matters connected with transport by various transport branches, for it establishes the extension of its application beyond transport by sea. The convention project has two aims: a. the establishment of a unified regime of liability; and b. the definition of the principles behind the use up to now of one transport document for an entire transport route. From the start it was known that the convention should apply to line transports, because these are marked by inequality in the positions of the parties involved. It may also, exceptionally, have application to tramp shipping in which there is equality of parties.