Data of the Crewboard port-to-port distance tool (https://crew-board.net/tools/port-distance)

network.json  Sea lanes derived from the Eurostat SeaRoute maritime network "marnet" (20 km resolution),
              https://github.com/eurostat/searoute, (c) European Union, licensed under the EUPL-1.2
              (LICENSE-EUPL-1.2.txt). Based on the Oak Ridge National Laboratory CTA Transportation Network
              Group Global Shipping Lane Network (2000), with additions from Eurostat.
              Converted by Crewboard: coordinates rounded to 0.001 degree, points stored as differences,
              the +180/-180 meridian joined. This derived file is distributed under the EUPL-1.2.
ports.json    Ports from the searoute-py package, https://github.com/genthalili/searoute-py,
              licensed under the Apache License 2.0 (LICENSE-APACHE-2.0.txt). Converted by Crewboard:
              name, country, UN/LOCODE and position only, duplicates removed.
land.json     Natural Earth 1:50m land, https://www.naturalearthdata.com, public domain. Simplified.