Lake Miike, Crater lake in Miyazaki Prefecture, Japan

Lake Miike is a crater lake in Miyazaki Prefecture, Japan, with a surface at 305 meters (1,000 feet) above sea level and a depth of 93.5 meters (307 feet), making it the deepest crater lake in the country. It has no outlet, and the water is held within a basin surrounded by forest, with a park and campsite on its shore.

The lake formed about 4,200 years ago when a steam eruption from magma created a crater that later filled with water. In the years after World War II, weapons and tanks were dumped into the lake, yet it remains a natural site today.

Along the lakeshore, local stories tell of seven ports that once existed, and the name of one, Oojikou, is still remembered in the area. Visitors can see the small park named after the birds that gather here, and in season the water attracts ducks and other waterfowl that people come to watch.

The lake is best reached by car, and the roads around it are narrow and winding, so allow extra time for the drive. The park and campsite provide parking and open spaces, but the trails into the surrounding forest are uneven and may not suit everyone.

Flat stones called Miike bora can be seen in the soil layers near the lake, a detail that geologists find interesting. The lake has no surface outlet, so its water level depends mainly on rain and underground seepage.