The right of foreign ships to navigate through a coastal state's territorial sea continuously and without prejudice to its peace or security.
In practice
For a master navigating near coasts, understanding innocent passage is important when transiting straits and archipelagic sea lanes, where variants of the right — transit passage and archipelagic sea lanes passage respectively — apply. Transit passage through straits used for international navigation (such as the Strait of Hormuz or the Strait of Malacca) cannot be suspended by the bordering state; innocent passage through ordinary territorial seas can be suspended temporarily for security reasons.
Regulatory detail & full definition
The right of innocent passage, codified in UNCLOS Part II Section 3, gives foreign ships the right to pass through the territorial sea of another state without prior authorisation, provided the passage is continuous and expeditious and does not prejudice the peace, good order, or security of the coastal state. Article 19 of UNCLOS lists activities that render passage non-innocent, including weapons exercises, surveillance, launching of aircraft, and the carriage of certain goods.
For a master navigating near coasts, understanding innocent passage is important when transiting straits and archipelagic sea lanes, where variants of the right — transit passage and archipelagic sea lanes passage respectively — apply. Transit passage through straits used for international navigation (such as the Strait of Hormuz or the Strait of Malacca) cannot be suspended by the bordering state; innocent passage through ordinary territorial seas can be suspended temporarily for security reasons.
Tankers carrying hazardous or noxious substances may be required by the coastal state to confine their passage to designated sea lanes. The master must ensure the vessel complies with traffic separation schemes and any ship reporting systems in force within the territorial sea. Violation of the conditions of innocent passage can result in the coastal state taking steps to prevent the passage, including exercising enforcement jurisdiction.