THE GEOGRAPHY OF TRANSPORT SYSTEMS
| Large | Medium | Small | Very Small | |
| Coastal Breakwater | 39 (29.8%) | 105 (33.2%) | 281 (23.8%) | 388 (13.0%) |
| Coastal Natural | 26 (19.8%) | 89 (28.2%) | 474 (40.1%) | 1529 (51.4%) |
| Coastal Tide gates | 5 (3.8%) | 5 (1.6%) | 18 (1.5%) | 11 (0.4%) |
| Lake or Canal | 3 (2.3%) | 6 (1.9%) | 26 (2.2%) | 32 (1.1%) |
| Open Roadstead | 18 (13.7%) | 17 (5.4%) | 97 (8.2%) | 450 (15.1%) |
| River Basins | 7 (5.3%) | 20 (6.3%) | 23 (1.9%) | 27 (0.9%) |
| River Natural | 25 (19.1%) | 59 (18.7%) | 248 (21.0%) | 518 (17.4%) |
| River Tide gates | 7 (5.3%) | 14 (4.4%) | 12 (1.0%) | 14 (0.5%) |
| Total | 131 (100%) | 316 (100%) | 1181 (100%) | 2875 (100%) |
Source: adapted from National Geospatial-intelligence Agency (2005) World Port Index, Eighteenth Edition, http://164.214.12.145/pubs/pubs_j_wpi_sections.html
The larger the port, the more likely investments were made to improve its sheltering (breakwater or tide gates) or capacity (basins).