Danish straits

Open·Constraint: The Danish Straits are three separate routes between the Baltic and the North Sea: the Great Belt,…·Alternative: None recorded

The passage stays open; its shallow routes charge in draft and pilotage.

What constrains it

The Danish Straits are three separate routes between the Baltic and the North Sea: the Great Belt, the Øresund and the Little Belt. The binding limit is local geography, not a Danish closure. Deep-draft ships must use the charted Route T through the Great Belt or the recommended route through the Sound, where narrow channels, shoals and heavy traffic make navigation demanding. DanPilot says route choice depends on draft and describes pilotage through the twists and turns of the straits (DanPilot, accessed September 16, 2026).

Rationing mechanism

No rationing mechanism is currently in force. The Copenhagen Convention abolished Denmark’s Sound Toll and established free passage for foreign commercial vessels, while the treaty bars Denmark from suspending that passage. Pilotage remains a safety service and a cost for some vessels, not an auction, convoy schedule or licence that allocates scarce transit slots (Gorrissen Federspiel, March 2024).

Incidence

Deep-draft tanker operatorsThey bear the cost of choosing the deeper Great Belt route and commonly taking local pilotage because the available channels, rather than a toll, determine how their cargo can move (DanPilot, accessed September 16, 2026).

Bulk shippersVessels with less draft can use shorter Great Belt routes, but their operators still pay for route restrictions and navigation support where shallow water and traffic narrow the practical choice (DanPilot, accessed September 16, 2026).

Marine insurersInsurers carry the collision and grounding exposure created by narrow, busy approaches, while the treaty-based right of passage limits Denmark’s ability to ration traffic through ordinary administrative control (Gorrissen Federspiel, March 2024).

Baltic importersThey absorb pilotage, routing and delay costs through freight rates because cargo bound for Baltic ports must use one of the limited maritime exits through the Danish Straits (Gorrissen Federspiel, March 2024).

Comparable passagesUnlike passages rationed by a canal authority or a war-risk convoy, the Danish Straits are governed by a treaty that protects passage; who decides is therefore the most useful comparison.