What are these four holes?

Yuhua Cave, located at the foot of day order Mountain in Jiangle County, Sanming City, Fujian Province, covers an area of 43 square kilometers. It is named after the smooth and radiant cave, and it is the largest limestone cave in Fujian Province. Cave scenic spots are formed in a long time with the participation of water and air under suitable climatic conditions.

Yuhua Cave has developed into five grades, from "one wind" at the entrance to "five nights" at the exit, and you can see 166 scenic spots. The total length of the whole cave is about 6 kilometers, and there are two passages, including six sub-caves, such as Zanghe Cave, Leigong Cave, Guozi Cave, Huangni Cave, Xiyuan Cave and Baiyun Cave, and three small galaxies, such as Shiquan, Jing Quan and Lingquan.

Shihua Cave, also known as Qianzhen Cave and Shibuda Cave, is located in Nancheying Village, Hebei Town, Fangshan District, Beijing. Shihua Cave, named after natural stone flowers, is the largest in China with various forms, colorful and huge quantity. The overall feature of Shihua Cave is that the cave body is multi-layered and multi-branched, with seven floors above and below, and the landscape of each floor is different, with a height difference of150m, which is known as the "underground pearl of Beijing".

Shihua Cave is a large karst cave found in China, with many caves, various sediments and a large number of secondary chemical sediments. Its aesthetic value and scientific research value can also rank among the top caves in the world.

3. reed flute cave is located on the Taohua River in the northwest of Guilin, south of Guangming Mountain. Because reed grows near the mouth of the cave, it is said that it can be made into a flute and blow out pleasant sounds, so it is named Reed Flute Cave. As far back as 1000 years ago, people came to reed flute cave in the Tang Dynasty, but it was not developed in previous dynasties. It was not until 1959 that exploration and construction began, and 1962 was officially opened to tourists.

Reed flute cave Cave is 240 meters deep and 500 meters long. There are many landscapes composed of stalagmites, stalagmites, stone pillars, stone curtains and stone flowers in the cave, which dazzle tourists. It is like a fairyland, and it is known as "the art palace of nature".

Yaolin Cave, also known as Yaolin Wonderland, is located in Tonglu County, Hangzhou City, Zhejiang Province. Yaolin Wonderland is divided into seven caves with a total length of about 1km and a total area of 28,000 square meters. It belongs to a typical karst landform and is a typical representative of karst caves in subtropical humid areas along the coast of central East China.

Yaolin Wonderland has attracted the attention of tourists from all over the world with its "secluded, deep, strange and beautiful" landscape and beautiful ecological environment since its opening. It is known as the "crown of all caves in China" with its magical terrain and magnificent stalactite scenery. It is one of the "Top 40 Tourist Attractions in China" and "Top 10 Tourist Attractions in Zhejiang Province".