The Brosno Dragon, or Brosnya, is a lake monster which is said to inhabit Lake Brosno near Andreapol in West Russia. It has been described as to resemble a dragon or a dinosaur. It is the subject of a number of regional legends, some that have been said to date back to the 13th century. Many people treat its existence skeptically and still claim it is not a dragon but a mutant beaver or a giant pike that is 100 to 150 years old. Others say that it is a group of wild boars and elk that cross the lake once in a while.
There are some scientific hypotheses about the dragon. Some think that the dragon is merely hydrogen sulfide gases going up from the bottom of the lake and making the water boil which in turn creates a dragon head, but the amount of hydrogen sulfide to make this would have to be enormous. There is also speculation that there is a volcano under Lake Brosno that is causing disturbances on the surface that are seen as something like a dragon. Fishermen say that the underwater world of the lake has several levels and that at times there are burbots and yellow perch that are in the lake. No one is entirely sure what is in Lake Brosno, but there are many possibilities as to what it is.