במדבר, פרק ל״ד, פסוק ו׳

Defining the edges of the Land of Israel involves looking toward the vast expanse of the Mediterranean Sea. Known to some commentators as the Spanish Sea [אבן עזרא, רבנו בחיי], this body of water sits to the west of the land [רש״י, רשב״ם, ביאור שטיינזלץ]. The sea does not merely rest alongside the edge of the country; the water itself serves as the actual boundary [רש״י, רבנו בחיי, אבן עזרא].

The legal definition of this border is naturally expansive. The primary approach among commentators is that the boundary extends outward to include the islands located within the sea, making them an inseparable part of the Land of Israel [רש״י, רשב״ם, שפתי חכמים, העמק דבר]. In rabbinic literature, these islands are called "nisin," a term derived from the word for a ship's mast. This name paints a vivid picture, as the tall trees growing on these distant islands look from afar like ships sailing with their masts raised high [בכור שור]. A complementary perspective adds that the boundary also captures the areas immediately adjacent to the shoreline, such as coastal reefs and shallow offshore lands [אוהב גר, ביאור שטיינזלץ].

Geographically and legally, the maritime border forms a straight, imaginary line stretching from the northwestern tip of the land at Mount Hor to the southwestern corner at the River of Egypt. Any area east of this line is considered part of the Land of Israel, while anything west of it falls outside the territory [רש ר הירש, בכור שור]. Including the sea and its islands within the national borders carries significant practical consequences. Produce grown on these islands is subject to agricultural laws, including mandatory tithes and the rules of the Sabbatical year. Furthermore, the sea itself holds the legal status of the land. This affects legal procedures, such as delivering a divorce document aboard a ship. It even applies to unique agricultural situations, such as a potted plant kept on a boat, which might become subject to tithing laws because it draws its nourishment from seawater that belongs to the Land of Israel [בכור שור].

Despite these detailed legal boundaries, the ancient understanding of maritime borders differed from modern concepts. During ancient times, the modern idea of territorial waters had not yet developed. Therefore, establishing this sea border was primarily about claiming sovereignty over the physical islands located within the area, rather than asserting total political control over the open water itself [ברכת אשר על התורה].