Zen rock gardens, also known as karesansui, are Japanese rock gardens that emphasize the natural beauty of stone arrangements without the use of plants. They typically feature raked gravel to represent water, rocks to symbolize islands or mountains, and often have a single, prominent stone or a small structure known as a bonze or a lantern that represents a person of enlightenment. The key characteristics include minimalist design, the use of natural elements, and an emphasis on the contemplative experience.