https://www.marineinsight.com/maritime-law/understanding-international-waters-boundaries-jurisdiction-and-legal-implications/ The starting point of international waters is generally recognised as the point where a nation’s territorial sea ends, usually 12 nautical miles from the baseline of a coastal state. This principle is enshrined in the United Nations Convention on the Law of the Sea (UNCLOS) under Article 3.
International waters are subject to the concept of “freedom of the high seas,” which grants states and individuals certain freedoms and rights. The article 87 (1) of the 1982 Convention, the freedoms of high seas expressly enumerate the following freedom: a) freedom of navigation;
b) freedom of overflight; c) freedom to lay submarine cables and pipelines; d) freedom to construct artificial islands and other installations permitted under international law; e) freedom of fishing; f) freedom of scientific research.
Certain activities are universally considered illegal in international waters. These include piracy, drug trafficking, human trafficking, illegal fishing, unauthorised dumping of hazardous materials, and engaging in acts of violence or terrorism.