Top: This turtle-shaped rock is one of nature's magical creations in Zhanjiang, Guangdong province. Above: The 2.3-sq-km lake shines like a jewel among lush vegetation at Huguangyan Geopark. Photos Provided to China Daily

A volcanic lake in Zhanjiang not only offers respite from the hustle and bustle of modern living, but a feat in distilling millenniums of ecological change into rocks of strange formations and animals of mythical origins, write Raymond Zhou and Li Wenfang.

The word "volcano" conjures up the image of a lone peak topped with an ash-strewn bowl-shaped crevice. If there is water in that crater, it would be like an invisible acrobat holding a cup of tea.

Huguangyan is nothing like that. The 2.3-sq-km lake sits comfortably on the ground, surrounded by lush vegetation and hardly a hint of hilly terrains. However, 160,000 years ago explosions 100 times the force of the atomic bomb dropped on Nagasaki - caused by the heating of groundwater and followed by billows of smoke and magma - erupted in this place 18 km to the southwest of what is now Zhanjiang, Guangdong province.

The lake is no doubt the jewel in the crown that is the 13.6-sq-km park. At an average depth of 22 meters, it is actually a "twin lake" caused by two adjacent blasts. A stretch of an island is visible as if it were a floating device, a telltale sign of what used to divide the two craters.

Technically, it is called a maar lake, named after a similar volcano-on-the-ground landform in Germany. But the original Maar Lake is much smaller while the one in Zhanjiang is the largest of its kind on Earth. In 2004, the two became "sister lakes" for the sake of scientific research. Photos of the German lake are displayed in the Volcano Museum inside the park for easy comparison.