The Brosno Dragon, also known as Brosnya (Russian: Бросня), is the name given to a lake monster which is said to inhabit Lake Brosno, near Andreapol in West Russia. It is described as resembling a dragon or dinosaur, and is the subject of a number of regional legends, some which are said to date back to the 13th century.
Rumors of a strange, giant creature living in Lake Brosno have existed for several centuries. One legend says that the lake monster scared to death the Tatar-Mongol army that headed for Novgorod in the 13th century. Batu Khan stopped the troops on the sides of Lake Brosno to rest. Horses were allowed to drink water from the lake. However, when the horses ventured down to the lake, a huge roaring creature emerged from the water and started devouring horses and soldiers. The Batu-khan troops were so terrified that they turned back, and Novgorod was saved. Old legends describe an "enormous mouth" devouring fishermen. Chronicles mention a "sand mountain" that appeared on the lake surface from time to time. According to another legend, some Varangians wanted to hide stolen treasure in the lake. When they approached the small island, a dragon came to the surface from the lake and swallowed the island up.
It was rumored in the 18th and 19th centuries that the giant creature emerged on the lake surface in the evening, but immediately submerged when people approached. It is said that during World War II the beast swallowed up a German airplane. Today, there are lots of witnesses who say they chanced to see Brosnya walking in the water. Locals say that it turns boats upside-down and has to do with disappearance of people.
Many people treat the existence of Brosnya skeptically and still say that the creature may be a mutant beaver or a giant pike of 100–150 years. Others conjecture that groups of wild boars and elks cross the lake from time to time.
There are some more scientific hypotheses concerning Brosnya. One of them is a gas version saying that when hydrogen sulfide goes up from the lake bottom it makes water boil up; this boiling in its turn resembles a dragon head. But the amount of hydrogen sulfide must be considerable to produce this effect. Other version says that there is a volcano in Lake Brosno that makes ejections on the water surface from time to time. It is well known that there are several fractures at the bottom of the lake, the depth and the direction of the fractures cannot be defined. It is not ruled out that the volcano crater is inside of one of the fractures. This explains why the volcano, if it actually exists, has not been discovered yet. See limnic eruption.
Fishermen say that the underwater world of Lake Brosno has a structure of several levels. From time to time, burbots and yellow perch can be found in the lake. For example, herring can be found in a lake in Peno District in the Tver Region. Some consider it strange that sea fish may live in the lake at all. Smelt shoals can be found in Lake Brosno as well. The phenomenon of Brosnya can be explained from the physical point of view: huge smelt shoals are reflected on the water surface through refraction of light and produces the effect of a huge reptile head. Physicists say that any mirage appears in hot weather. Indeed, witnesses say that they came across Brosnya in summer. However, the origin of the rumors of this strange monster remain a mystery.