Terminal depth represents the available draft at existing terminals that can differ from channel depth, which is the draft of the port access channel(s). Docking depth and pier length may limit the number of slots that can accommodate a deep draft vessel within a port. The drafts of a large sample of commercial ports reveal two major clusters. The first is around the Panamax standard of about 12 meters, and the second is around 15 meters, which is the New-Panamax standard. The introduction of larger containerships, namely the post-Panamax plus class (draft above 12 meters), imposes limitations in available port calls. Draft considerations have become a key component in the commercial viability of ports.