How we build the Maritime Radar

The data come from IMF PortWatch, the International Monetary Fund’s open platform that monitors global maritime activity using AIS signals (the positioning system broadcast by vessels), processed on the United Nations Global Platform. It covers 2,065 ports and 28 maritime chokepoints with daily data since 1 January 2019. We query the source once a day (last run: 23 September 2026) and keep a full copy in our warehouse: the website never queries the IMF live.

The maritime activity indicators in this section are built from vessel AIS signals. Volumes are estimates — the IMF calculates them from each vessel’s capacity and draught — and may be revised. They are not equivalent to the official statistics published by port authorities: they may include transhipment, AIS coverage is not perfect in every area, and the polygon PortWatch assigns to a port does not exactly match the statistical scope of its port authority. For official Spanish data, see our port traffic and foreign trade sections.

• Port calls: movements of cargo vessels and tankers detected at each port. They are not the port authority’s “official port calls”.
• Estimated volume: metric tonnes of cargo the IMF estimates were loaded and unloaded, broken down into imports and exports and by vessel type (container, dry bulk, general cargo, ro-ro and tanker).
• Transits and capacity at chokepoints: vessels crossing each of the 28 critical chokepoints — the Strait of Gibraltar among them — and their estimated cargo capacity.
• TradeNow: a monthly nowcast of each country’s foreign trade that the IMF estimates from AIS activity, weeks ahead of customs data.

Daily data are noisy (weekends, public holidays, storms). That is why we use the 7-day moving average as the main indicator and the 28-day average for the underlying trend. The year-on-year change compares the 7-day average with that of the same days 52 weeks earlier (364 days), so that Tuesdays are not mixed with Sundays. The latest published days may be revised: each run re-imports the last two weeks and, if a value changes, the previous one is archived — we never overwrite silently.

Source: IMF PortWatch / UN Global Platform. Calculations and processing: EED Data (moving averages, changes and indices are ours). The IMF’s data policy allows reuse with attribution; the data are provided “as is” and may be revised by the source.