What makes an island an islet, and why does the distinction matter for nations?

Nature · Published 3 October 2026 Swipe more like this →

In short: An islet is more than just a small island. While definitions are notoriously imprecise, these tiny landforms—often barren, rocky, or temporary—carry immense weight in international law. Whether a piece of land is classified as an islet or a rock can fundamentally alter a country's maritime borders and economic rights.

At its core, an islet is a diminutive landform, derived from the Old French term islette. While there is no universal rule for size, which can range from a few square feet to several square miles, these features are generally characterized by a lack of vegetation and an inability to support human life. They appear in diverse forms, from sandy cays in the Caribbean to rocky skerries in Ireland and coral-based motus in Polynesia. Some are permanent, while others are tidal, appearing only when the water level drops.

The classification of these features is far from academic; it is a matter of high-stakes geopolitics. Under international maritime agreements, specifically the rules governing the law of the sea, the status of a landform dictates its legal reach. If a feature is deemed a rock incapable of sustaining human habitation or independent economic activity, it is denied an exclusive economic zone or a continental shelf. This distinction has fueled long-standing territorial disputes, such as the case of Snake Island, where the classification of the land directly impacted national claims.

Despite these rules, international legal bodies do not always prioritize the status of an islet when resolving border conflicts. The International Court of Justice has, on occasion, bypassed the inhabitation status of these features entirely. For instance, in 2009, the court set aside certain islets during the adjudication of a maritime dispute between Romania and Ukraine. A similar approach was taken in the case involving Libya and Malta, where the islet of Filfla was effectively ignored in the final decision. These examples highlight the tension between strict legal definitions and the practical, often pragmatic, realities of international diplomacy.

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