UNCLOS transit passage is the regime governing navigation through straits used for international navigation. It is set out in Part III (Articles 37–44) of the 1982 United Nations Convention on the Law of the Sea (UNCLOS).
It is deliberately broader and more protective of freedom of navigation than the “innocent passage” regime that applies in ordinary territorial seas.
3. Duties of ships and aircraft in transit (Article 39)While exercising the right, vessels and aircraft must:
5. No charges for mere passage: Coastal states may not levy charges on foreign ships merely by reason of their passage through the strait. They may only charge for specific services rendered to the ship (e.g., pilotage, towage, or other services actually provided).
The Strait of Hormuz is used for international navigation to which the transit passage regime applies (or would apply as customary international law, even for non-parties such as Iran). Because the strait is less than 24 nautical miles wide at its narrowest point, the territorial seas of Iran and Oman meet or overlap, leaving no high-seas corridor. The transit passage rules are therefore the primary legal framework that protects free navigation through it.
In short: transit passage prioritizes the continuous, unimpeded flow of international shipping and aviation through critical chokepoints while still allowing the bordering states limited regulatory authority that does not undermine that freedom.
Core Concept
Transit passage is the right of ships and aircraft to continuous and expeditious passage through a strait that connects one part of the high seas or an exclusive economic zone (EEZ) to another part of the high seas or an EEZ.It is deliberately broader and more protective of freedom of navigation than the “innocent passage” regime that applies in ordinary territorial seas.
Key Features
1. Right of transit passage (Article 38)- All ships and aircraft (including warships, submarines, and military aircraft) enjoy the right of transit passage.
- Passage must be continuous and expeditious.
- Submarines may transit submerged (they do not have to surface and show their flag, as they must in ordinary territorial seas under innocent passage).
- Aircraft may overfly the strait.
3. Duties of ships and aircraft in transit (Article 39)While exercising the right, vessels and aircraft must:
- Proceed without delay.
- Refrain from any threat or use of force against the sovereignty, territorial integrity, or political independence of the coastal states.
- Refrain from any activities other than those incidental to normal modes of continuous and expeditious transit (unless rendered necessary by force majeure or distress).
- Comply with generally accepted international regulations, procedures, and practices for safety at sea and for the prevention of pollution.
- Aircraft must observe the Rules of the Air and monitor the appropriate radio frequency.
- Safety of navigation and the regulation of maritime traffic (including traffic separation schemes).
- Prevention, reduction, and control of pollution.
- Prevention of fishing.
- Loading or unloading of any commodity, currency, or person in contravention of customs, fiscal, immigration, or sanitary laws.
- Be non-discriminatory.
- Not have the practical effect of denying, hampering, or impairing the right of transit passage.
- Be given due publicity.
- Conform to generally accepted international standards where relevant (especially for pollution and safety of navigation).
5. No charges for mere passage: Coastal states may not levy charges on foreign ships merely by reason of their passage through the strait. They may only charge for specific services rendered to the ship (e.g., pilotage, towage, or other services actually provided).
Transit Passage vs. Innocent Passage
| Feature | Transit Passage (Straits) | Innocent Passage (Territorial Sea) |
|---|---|---|
| Scope | Straits used for international navigation | Ordinary territorial seas |
| Submarines | May remain submerged | Must surface and show flag |
| Aircraft | Right of overflight | No right of overflight |
| Suspension | Cannot be suspended | Can be temporarily suspended |
| Activities allowed | Continuous & expeditious transit | Passage that is not prejudicial to peace, good order, or security |
| Charges | Only for specific services | Only for specific services |
Application to the Strait of Hormuz
The Strait of Hormuz is used for international navigation to which the transit passage regime applies (or would apply as customary international law, even for non-parties such as Iran). Because the strait is less than 24 nautical miles wide at its narrowest point, the territorial seas of Iran and Oman meet or overlap, leaving no high-seas corridor. The transit passage rules are therefore the primary legal framework that protects free navigation through it.
In short: transit passage prioritizes the continuous, unimpeded flow of international shipping and aviation through critical chokepoints while still allowing the bordering states limited regulatory authority that does not undermine that freedom.