The Grisons is Switzerland's largest canton. It is also its easternmost canton. Its geography, essentially marked by the Alps, is complex and encompasses a wide range of climates and ecosystems. It is one of the three large southern Alpine cantons, along with Ticino and Valais, which comprehend regions on the south side of the Alps. But contrary to those (and all other cantons), it fully extends on both sides of the great Alpine barrier, from the northern plains at Maienfeld to the southern plains at Roveredo. However, a large portion of the canton is neither clearly north nor south of the Alps, it is the Engadin (the "garden of the Inn"), a large inner Alpine valley oriented towards eastern Europe. Therefore the canton comprehends four of the five drainage basins of the country. The north of the canton is drained by the Rhine (ending in the North Sea), the south by the Po and Adige through several affluents (Mediterranean Sea), and the Engadin by the Danube though the Inn (Black Sea).