Between 7500 and 2500 years ago, a space object composed of coarse octahedrite fell into Earth’s gravity well and broke into huge flaming pieces. Although much of the object’s mass and velocity were lost passing through the atmosphere, a number of large pieces (with a total mass estimated to be about eighty tons) struck the Saareemaa island in what is now northern Estonia. Since these fragments were traveling between 10 and 20 kilometers per second, a substantial amount of kinetic energy was released: the impact probably had approximately the same energy yield as the Hiroshima atomic bomb. The area was inhabited by Bronze Age humans and those who were not incinerated must have been appalled when a ball of incandescent hellfire swallowed a whole forest with deafening thunder.
The impact formed the Kaali crater field. Since the impact occurred so recently, the craters are still quite pronounced. The largest crater has a diameter of 110 meters (330 feet) and contains a freshwater lake at its bottom. The smallest crater (which I unfortunately could not find a picture of) is only about 10 meters across and a meter deep.
As at Lake Lonar and the Great Serpeant Mound Crater, there is sacred architecture affiliated with the Kaali Crater field. During the Iron Age, unknown masons constructed a 470 meter long stone wall around the lake. Since the body of water is nearly a perfect circle it looks deceptively small but, aas you can see in the picture at the top, the lake is actually large and deep. Kaali Lake has been a sacred lake for a long time and local reverence suggests that it still is. Additionally, numerous domestic animal remains from the area around the lake indicate that the area has been a sacrificial ground for thousands of years. In fact some animal sacrifices date as recently as the 17th century—it seems that Estonia’s conversion to Christianity did not preclude some surviving pagan traditions. Certain stories from Finnish mythology seem to relate to the lake: one tale relates how a trickster god stole the sun. The virgin goddess of the air, trying to make manufacture a second sun let a flaming spark fall down—it drifted into the forested islands south of Finland and caused a great fire which humankind saved and used for heating, cooking, and forging.