In winter, rivers and lakes can freeze - this is not uncommon.
The ice circle became the concern of the researchers because at first glance, it did not seem to be moving but was actually spinning at a steady speed.
Amateur photographer Daniel Norrie, 31, has captured a unique image on the Helmsdale River area in Scotland.
Owning a special charm, Lake Baikal deserves to be considered a paradise under the earth.
A retired engineer hunted in North Dakota, USA last Saturday spotted an ice circle more than 15 meters in diameter on the Sheyenne river.