What is it like to bathe at Kotan on frozen Lake Kussharo?

Where is Kotan-no-yu and how do you reach it?

The bath sits on the beach of Kotan village on the southeast shore of Lake Kussharo in Teshikaga town. From JR Kawayu Onsen Station it takes about 20 minutes by car along Prefectural Road 52, and Akan Bus runs out from the station as well. Winter tyres are a given on any road this far east.

For a bed, Kawayu Onsen lies about 11 km north as the crow flies, and its public bath Yukichi lets tattoos in for ¥500. The bigger hotels are at Akan. The nearest lift turns at Akan Lakeside, where Akanko Onsen's town hill runs one chair above the frozen lake and plans to open for 2026/27 on 25 December. Kotan suits the rest day on a trip that swings east, or the drive between Akan and Kawayu.

What is the bath like in winter?

Grey boulders hold the pool right at the waterline, and one big rock in the middle splits it into a men's half and a women's half. Each side has its own changing room. Nothing screens the pool from the beach, so anyone walking along the shore can see in. Swimsuits are allowed.

The water is a clear sodium bicarbonate spring that runs in straight from the source. None of the listings we read publish its temperature. Put a hand in before you climb down.

In the coldest weeks Lake Kussharo freezes from shore to shore, and the ice shoves itself up into pressure ridges across the surface as the temperature swings. Whooper swans fly in from Siberia for the winter. The Japanese encyclopedia entry on Kotan notes that the spring-warmed shallows beside the bath draw them in, and the national park guide describes the same scene a little further along the shore at Sunayu. Sit low with snow on the boulders at eye level and the birds preen a stone's throw away. Give them room.

What rules does Kotan-no-yu ask you to follow?

Signs at the bath ask for quiet at night. Camping is banned, and so is eating or drinking in the bath. The owner of a craft shop in the village looks after the pool and keeps it clean, so carry out everything you bring, down to the bottle caps.

Plan on finding no taps. Scoop a little water over your shoulders and legs before you get in, and keep soap out of the pool entirely. Bring your own towel and leave it on a rock. Our onsen etiquette guide walks through the rest of the routine.

What should you bring for a winter soak?

Pack a bath towel and a dry one for afterwards, plus slip-on shoes for the few steps from the changing room to the rocks. A swimsuit helps if you plan to soak in daylight with people on the beach. Since the bath never closes outside the Friday clean, a night soak under a clear sky works too, and a headlamp keeps you off the icy stones on the way in. Switch it off once you're in the water so you don't light up the bathers on the other side of the boulder. Keep a down jacket by the changing room door for the walk back to the car.

Can you bathe at Kotan with tattoos?

Yes. Kotan-no-yu has no staff and posts no tattoo rule, so tattooed bathers soak like anyone else. A swimsuit covers whatever you'd rather keep to yourself. If you want a staffed bath afterwards, Kawayu's Yukichi accepts tattoos, and its acidic water will take the shine off a watch, so leave the metal in the car.

Who lives in Kotan?

Kotan is the Ainu word for a village, and Ainu craft shops line this one today. The person who keeps the bath clean runs one of them. The lake takes its name from Ainu too. Kutcharo names the throat of a lake, where its water leaves as a river, and at Kotan the Kushiro River begins its run south to the Pacific.

The Teshikaga Town Kussharo Kotan Ainu Museum stands in the village and charges ¥420 for adults. Its 25-minute English film covers Ainu history from the discrimination of the Meiji era to the community groups who pass on song, dance, festivals and language now. Plan a separate trip for it, because the museum closes over winter. The town's 2025 Ainu policy plan has it open from early April to the end of November, so a February soak misses it. Phone 015-484-2128 to check the current season. In winter, our Akan page covers the Ainu kotan on the shore of Lake Akan.

What else is nearby on Lake Kussharo?

Wakoto Onsen sits about 3 km away at the neck of the Wakoto Peninsula. Its free rotenburo stays open around the clock, and the neutral simple spring leaves the ground at 52.5°C, so the tub can run hot. Whooper swans gather on the open water there as well.

Sunayu, along the east shore, lets you dig into warm sand where hot groundwater rises under the beach. Its rest house opens free of charge every day from 8:00 to 17:00. Kawayu's steaming Iozan and the town's free foot baths fill the rest of a short day.

How we researched this

We compiled this from the Hokkaido Tourism Organization and other tourism listings, the Japanese and English encyclopedia entries, the national park guide, the Forestry Agency's place-name notes and the town's published plans, read in October 2026. Nobody from Ride Hokkaido has bathed at Kotan for this piece. Cleaning days and museum seasons change, so check them before you drive out.

Sources

• Hokkaido Tourism Organization: Kotan-no-yu
• Rurubu: Kotan-no-yu
• Mapple: Akan and Mashu in winter
• Wikipedia (Japanese): Kotan Onsen
• Wikipedia: Lake Kussharo
• Japan National Parks: Sunayu Rest House
• Forestry Agency: Kawayu landscape forest and place names
• Japan Tourism Agency: Teshikaga Town Kussharo Kotan Ainu Museum
• Rurubu: Kussharo Kotan Ainu Museum
• Cabinet Office: Teshikaga Ainu policy plan, March 2025