Lake Ikeda and the Legend of Isshi
Lake Ikeda, a caldera crater lake located inland in the Ibusuki region, is the largest lake in Kyushu. With a circumference of approximately 15 kilometers and a 4-kilometer diameter, it is also the fourth deepest lake in Japan, at a maximum depth of 233 meters.
The lake was formed after a volcanic eruption between 5,500 and 5,700 years ago, during the Jomon period (10,000–300 BCE). Five cubic kilometers of volcanic matter, including pumice and ash, were ejected from the volcano. As a result, the ground collapsed, forming a caldera, and over time rainwater filled the depression to create Lake Ikeda.
Lake Ikeda’s volcanic activity continues to this day. A lake-bed volcano approximately 1 kilometer in diameter lies beneath the surface, rising 150 meters from the lake’s bottom.
The lake is also home to a colony of giant mottled eels, designated a Natural Monument of Ibusuki City in 1969 due to their unusual size. The eels can reach 1.8 meters in length and have a girth of up to 50 centimeters.
According to local legend, the eels are not the only enormous creatures living in the lake, as the sighting of a large beast in 1978 has inspired tales similar to those surrounding the Loch Ness monster. Is the mysterious Isshi, whose name resembles Scotland’s Nessie (pronounced “Nesshi” in Japanese), a dinosaur that somehow survived extinction? Or is Isshi nothing more than a particularly large giant eel or fish?
Be sure to carefully scan the lake’s surface: Even if you don’t spot Isshi, you might catch a glimpse of a giant eel.
