Sea network for Shiptrail's route preview
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Sea routes: the shortest path over Eurostat's SeaRoute maritime network (EUPL-1.2), which builds on the Global Shipping Lane Network, courtesy of Oak Ridge National Laboratory, U.S. Dept. of Energy, with European coastal lines from AIS. Simplified and converted to a compact file. Not for navigation.

What this is
  sea-network-d2ffc78a.json is a derived work of the maritime network in Eurostat's SeaRoute
  (file marnet_plus_10km.gpkg, the 10 km resolution of "marnet_plus").

Where it comes from
  Eurostat, SeaRoute: https://github.com/eurostat/searoute
  Source file SHA-256: 738cf880623dee8be3616a3ca46b565cc47a6548003ebd4438fea309dc7fa4f9
  Eurostat's network builds on the Global Shipping Lane Network (World, 2000)
  of the Oak Ridge National Laboratory CTA Transportation Network Group,
  courtesy of Oak Ridge National Laboratory, U.S. Dept. of Energy, enriched
  by Eurostat with lines around the European coasts drawn from AIS data and
  with inland lines.

What was changed (tools/build-sea-network.mjs)
  - Read from the GeoPackage and joined into a graph of nodes and edges.
  - Coordinates rounded to 0.0001 degree (11 m).
  - The two Arctic passages (labelled northwest and northeast) removed.
  - Only the largest connected piece kept.
  - The Suez, Panama, Kiel and Corinth canals marked by their edge numbers;
    every other passage label dropped.
  - Written as one line of JSON, with coordinates and edges as differences.
  Converted on 2026-10-30.

Licence
  European Union Public Licence v. 1.2 (EUPL-1.2): https://interoperable-europe.ec.europa.eu/collection/eupl/eupl-text-eupl-12
  The licence text as Eurostat ships it is in sea-network-LICENSE.txt. This
  file is distributed under the same licence.

Not for navigation. The routes drawn from it are the shortest ways between
two ports along the shipping lanes of the network, not any ship's plan.