Mengdong River Flat Lake Scenic Area lies on the lower reaches of the Mengdong River, stretching from Monkey’s Leap upstream to Dragon Gate Gorge downstream for a total length of 45 kilometers (including a section of the Youshui River). This flat lake was formed by rising reservoir water following the completion of the Fengtan Hydropower Station on the lower Youshui River.

Steep stone cliffs rise vertically along both banks of the lake, shaded by towering ancient trees and dotted with numerous karst caves and jagged rock formations. The area features 15 major scenic spots: Dragon Gate Gorge, Guanyin Cave, Octave Melon Stone Cave, Golden Lion Cave, Mandarin Duck Gorge, Golden Toad Cave, Broken-Arm Rock, March Cauldron Temple, Little Dragon Cave, Great Sage Gorge, Yin-Yang Divine Wind Cave, Monkey’s Leap, Fairy Maiden Gorge, Romantic Rock and Laosi Rock. It is reputed as the "Little Three Gorges". The valleys flanking the waterway teem with rare birds, beasts and plants, forming a natural botanical and zoological garden. The scenic zone has been listed as one of Hunan’s Top Ten Scenic Spots.

(Dragon Gate Gorge)

Local villagers say Little Dragon Cave was the cultivation retreat of the Third Prince of the Dragon King. Carved into a sheer cliff over 20 meters high on the west bank of Mengdong River, the cave is sheltered by ancient trees above and bordered by calm lake water below. A huge clear circular pool sits at the cave entrance. Water overflows the pool along the cliff face to form a waterfall. Visitors may row a small boat to the back wall of the pool, then pass through a narrow stone crevice more than 10 meters long and 1.5 meters wide, beyond which the cave suddenly opens up to reveal a spectacular array of landscapes. Key sights inside include Dragon Palace Ballroom, Monkey King Stealing Treasures, Under-Sea Snow Mountain, Mountain Great Wall and Turtle Holding Eggs. Countless stalagmites and stone drapes take endlessly varied shapes—resembling dragons, lions, villages and stockades, creating a dazzling gallery of natural sculptures.

The Swan Lake on the third level of the cave is especially breathtaking. Oval-shaped and covering a full 80 square meters, the lake stirs ripples even without wind, as if invisible dragons churn the waves. A waterfall cascades down the back wall like flowing brocade, and stalactites beneath the falls form swan-shaped stone formations poised as if ready to take flight, an incomparably marvelous sight. The cave’s most distinctive feature—rivers winding within the main river and smaller caves nested inside the main cavern—makes it a one-of-a-kind natural wonder.

Monkey’s Leap is located along the Niulu River reach. Towering sheer cliffs press close together on both banks. When boating through the water, visitors only catch a thin strip of sky overhead. Monkeys can bound freely back and forth across the narrow gap between the two cliffs, hence the name "Monkey’s Leap".

(Monkey’s Leap)

The valleys lining Mengdong River’s natural botanical and zoological garden host abundant rare wildlife. Bird species include golden pheasants, wild pheasants, silver pheasants, thrushes, turtledoves, bamboo partridges, cuckoos, red-billed leiothrixes, cliff eagles, common cuckoos, owls and various other small songbirds. Mallards and mandarin ducks also inhabit the river, gliding across the water in pairs.

Among mammals, monkey troops form the dominant local population, alongside river deer, muntjac, civets, hedgehogs, martens and wild boars. Tigers are rarely seen, though transient mountain tigers are said to wander through the area each spring and summer. Elders recount that rhinoceroses once lived here, and the local Hand-Waving Folk Song describes the rhinoceros’s appearance and habits in detail. The valleys are home to many snake species, while the river abounds in fish, with giant salamanders, soft-shell turtles and mandarin fish being unique native species of the Mengdong River. Lush, diverse vegetation blankets both riverbanks, marking this region as an intact primeval forest zone.