In the Imotski region, which is halfway between Mostar and Sinj, large craters formed by the Imotski lakes, the Red Lake and the Blue Lake, can be seen. Here, even the river Vrlika possesses unusual features: it runs through the plain for about 15 km, then disappears underground to reappear about 50 km further down in the Popova region as the river Trebisnjica.