Kagami Numa is a mythical Japanese lake that turns into a giant eye every spring, during the thawing process, hence its nickname, Dragon’s Eye Lake.

Located near the summit of Mount Hachimantai in north-eastern Japan, in the middle of a dense forest, Kagami Numa doesn’t look much different than the many other volcanic lakes in the area, most of the year. But for about a week – ate May to early June – it turns into a giant blue eye that inspired its intriguing nickname, Dragon’s Eye Lake. The unique appearance of the circular lake during this one week has inspired a legend of two dragons in love that chose this body of water as their meeting spot.

Although many people choose to believe the legend of the lake over science, when it comes to explaining its eye-like shape, the magic does have a plausible explanation. During the spring thaw, pressure from the water’s depths causes the snow to gather only in the middle of the lake, creating a pupil-like shape with a ring of blue water around it.

In windy weather, the snow-covered piece of ice in the center rotates, giving the impression of a moving pupil. It’s a fascinating natural phenomenon, and it’s no wonder that many people from all over Japan and even from abroad flock to Mount Hachimantai at the end of spring just to see it first hand.

In recent years, photos of Dragon’s Eye Lake shared on social media and a popular video posted by the BBC have made Kagami Numa an even more popular tourist attraction.

For more awe-inspiring tourist attractions, be sure to check out Japan’s heart shaped lake, and the beautiful Monet’s Pond.