Researchers Pablo Kaluza, Andrea K¨olzsch, Michael T. Gastner, and Bernd Blasius at Institute for Chemistry and Biology of the Marine Environment, and Carl von Ossietzky University, Oldenburg, Germany use information about the itineraries of 16,363 cargo ships during the year 2007 to construct a network of links between ports.

They show that the network has several features which set it apart from other transportation networks. Most ships can be classified in three categories:(right)  bulk dry carriers, container ships and oil tankers. These three categories do not only differ in the ships’ physical characteristics, but also in their mobility patterns and networks.

Container ships (right)  follow regularly repeating paths, where bulk dry carriers and oil tankers move less predictably between ports. The network of all ship movements possesses a heavy-tailed distribution for the connectivity of ports and for the loads transported on the links, with systematic differences between ship types.

The data analysed in this paper improve current assumptions based on gravity models of ship movements, an important step towards understanding patterns of global trade and bioinvasion.

Despite carrying 90% of the planet's trade, nobody until now mapped the network of links between the world's ports.

The International Maritime Organization based in London estimates that 90% of the world's trade is moved around the planet by sea. Given the fascination that complexity scientists have with rail, air and road networks, it seems strange that so little attention has been paid to the maritime network.

However, the maritime network shows some surprising differences from the network that flight paths make between airports. For example, on average, it takes just 2.5 jumps to move from one port to another on the maritime network compared to an average of 4.4 to move between one airport and another. The maximum shortest path between ports is 8 jumps while between airports it is 15 jumps. It looks to be decidedly easier to travel the world by ship than by plane, at least in some respects.

Maritime network are also decidedly asymmetric: more than half of all ports are linked in only one direction, meaning that cargo ships do not routinely make round trip journeys between ports.

Perhaps most interesting of all is that different types of ship move in different patterns. While container ships tend to follow regular schedules, bulk dry carriers and oil tankers movements are less regular because their routes are determined by the price of the commodities they carry and which vary enormously and bulk dry carriers and oil tankers also more likely to sail empty.

One of the most significant methods of cross species invasion is from water sucked into ships' ballast tanks in one part of the world and discharged in another; a particularly important factor when ships sail empty. So the new network map should give marine biologists an insight into how bioinvasion occurs and what steps they can take to tackle it.

The  "World Bank Logistics Performance Index 2010" released by  Robert B Zoellick, President of The World Bank, LPI 2010 assesses the Trade Logistics performance of 155 countries. Currently the top 10 countries are according to this list:
1. Germany 4.11
2. Singapore 4.09
3. Sweden 4.08
4. Netherlands 4.07
5. Luxembourg 3.98
6. Switzerland 3.97
7. Japan 3.97
8. UK 3.95
9. Belgium 3.94
10. Norway 3.86