Grenada is by far the largest, with a width of 12 miles (18km) and a length of 21 miles (34km), comprising mountainous, volcanic terrain. This topography provides Grenada with one of the loveliest and most varied environments in the Caribbean, including crater lakes, as well as a variety of plant and animal life. Dwarf forests high atop Mount St Catherine descend to the rainforests of middle altitudes, which give way in turn to the dry forests of the lowlands. Those forests shift to mangrove at the coast, giving way to stunning white sand beaches, brilliant blue water and exquisite coral reefs.