Karesansui watergrass tank

Quick answer：

Karesansui, also known as dry landscape or Zen garden, is a traditional Japanese garden style that uses rocks, sand, and sometimes moss to represent natural scenery. A watergrass tank is a type of karesansui garden that includes a water element, often in the form of a small pond or stream, alongside the rock and sand arrangements. This combination of water and the minimalist rock garden is meant to evoke a sense of tranquility and the beauty of nature in a compact space.