The coastline of Haiti is irregular and forms a long southern peninsula and a shorter northern one, between which lies the Gulf of Gonâve. Rising from the coastal plains to a peak height at La Selle of 2,680 m (8,793 ft) and covering two-thirds of the interior, three principal mountain ranges stretch across the country; one runs east and west along the southern peninsula, while the others stretch northwestward across the mainland. Once-fertile plains run inland between the mountains: the Plaine du Nord, extending in the northeast to the Dominican border, and the Artibonite and Cul-de-Sac plains reaching west to the Gulf of Gonâve. Of the many small rivers, the Artibonite, which empties into the Gulf of Gonâve, and L'Estère are navigable for some distance.