A closed beach is never just closed. Behind every ban there is a specific reason, written down somewhere, with a specific body enforcing it. On one island it is a 1956 regulation drawing a five nautical mile circle around people who have never joined the modern world. On another it is 85,000 cubic metres of nuclear waste under a cracking concrete lid. Elsewhere it is a viper that exists nowhere else, a runway built after a population was removed, an anthrax burial pit, a heron colony, or simply a family that has owned the place since 1864. The 27 islands and beaches here are grouped by the reason they are shut, because the reason is the interesting part. Some bans protect the visitor. Most protect the island from the visitor. A few protect a legal claim, and one is enforced by nothing but the North Atlantic.
North Sentinel Island, India: A Five Nautical Mile Ring Around Uncontacted People
The Andaman and Nicobar Islands Protection of Aboriginal Tribes Regulation, passed in 1956, makes it illegal to travel to the island or to come within five nautical miles of it. The mechanism is quarantine in both directions. The Sentinelese have lived in isolation for thousands of years and carry no acquired immunity to mainland infections, so a single visitor with a chest cold functions as a weapon. Indian Navy patrols back the rule up. In November 2018 an American missionary, John Allen Chau, paid local fishermen to drop him near the reef and tried to land on three consecutive days. On 17 November the fishermen watched islanders drag his body up the beach and bury it above the tide line. India did not prosecute the Sentinelese and never recovered the body, because recovering it would have meant landing.