Lake Suwa

Where it sits. Lake Suwa lies at 759 metres in a tectonic basin in central Nagano Prefecture, where the Median Tectonic Line and the Itoigawa-Shizuoka fault meet — the lake occupies a pull-apart basin created by that intersection, not a volcanic crater. It is the largest lake in Nagano at roughly 13 square kilometres, but also strikingly shallow, with a maximum depth of about seven metres, and a shoreline of some 16 kilometres ringed almost entirely by a flat paved path. Three municipalities sit on its shores: the city of Suwa on the south-east, Okaya at the outflow, and the town of Shimosuwa on the north. The Tenryū River begins here and runs south to the Pacific. Ridges rise on all sides, and on clear winter days Mount Fuji appears in a notch to the south-east.

Ice, gods and the world's longest climate record. In cold winters the frozen surface cracks and buckles into pressure ridges thirty centimetres high or more that run across the lake in lines. This is the omiwatari, understood in local Shinto tradition as the track left by Takeminakata, the god of Suwa, crossing to visit the goddess Yasakatome on the far shore. Priests of Suwa Taisha have recorded its appearance, direction and date since 1443, which makes it the oldest continuous human observation of a climate phenomenon anywhere in the world, and the series is now used in scientific literature on warming. The record also tells a blunt story: in the seventeenth century the crossing failed to form twice; in the twenty-five years to 2025 the lake failed to freeze in eighteen of them, and the last ridge, in 2018, was only a few centimetres high.

What surrounds it. Suwa Taisha, one of the oldest shrines in Japan, is spread across four separate compounds on both sides of the lake — the Upper Shrine's Maemiya and Honmiya, the Lower Shrine's Harumiya and Akimiya — none of which has a honden in the usual sense; the god is held to reside in the mountain and in the trees. Every six years, in the years of the monkey and the tiger, the Onbashira festival hauls sixteen huge fir trunks down from the hills by rope and human muscle, including the kiotoshi, a plunge down a steep slope with riders still astride the log. Kami-Suwa on the eastern shore is a hot-spring town with a lakeside geyser, and Takashima Castle, built at the end of the sixteenth century and rebuilt in 1970, once stood with water on three sides and was nicknamed the floating castle of Suwa. The basin is also a precision-industry heartland — Seiko Epson was founded and remains headquartered in Suwa — which is why the area was once called the Switzerland of the East. On 15 August the Lake Suwa Fireworks Festival fires tens of thousands of shells over the water, the sound rebounding off the surrounding ridges; it is among the largest such events in Japan and fills every room in the basin.

On screen, and here scepticism is required. Search for Suwa and you will find it named as the model for Itomori, the lakeside town of Your Name (2016). That claim is fan attribution, not a studio statement. Makoto Shinkai grew up in Koumi, elsewhere in Nagano, and the resemblance people notice — a ring of mountains, a lake with a small town on its shore, a shrine culture with old rope-and-timber ritual — is a resemblance to Nagano generally rather than to Suwa specifically. Itomori is explicitly fictional, its lake is a meteor crater, and Suwa's basin is tectonic. The film's confirmed real locations are elsewhere: Hida-Furukawa in Gifu for the town scenes, and Yotsuya in Tokyo for the closing staircase. Suwa is worth the trip on its own merits; it is not a place where you can stand in a frame from the film.

Walking, cycling and eating. The lakeside circuit is flat, continuous and about 16 kilometres, with rental bicycles at several points and a walking pace of roughly four hours. Free public foot baths sit along the Kami-Suwa shore. The lake's fisheries yield wakasagi smelt, fried whole, and eel is a Suwa speciality of long standing. Katakura-kan, a 1928 public bathhouse in the town built by a silk-industry family, still operates its enormous tiled communal pool.

Getting there and timing. Limited expresses on the Chūō Main Line reach Kami-Suwa from Shinjuku in about two and a quarter hours; drivers use the Chūō Expressway. Late April to June and October give the clearest air and calmest water. August is the fireworks and the crowds, and winter mornings are cold, still and increasingly ice-free.