The beautiful caldera lake of Tōya-ko (洞爺湖) is punctuated dead centre by the conical island of Nakajima. Its southern shore is home to the tired-looking resort Tōya-ko Onsen (洞爺湖温泉), where you’ll find most accommodation and local transport connections. Between April 28 and October 31 spectacular fireworks (nightly 8.45–9.05pm) illuminate the lake. Pretty as the location is, the best reason for visiting Tōya-ko is to see the nearby active volcano Usu-zan (有珠山), around 2km south, and its steaming “parasite volcano” Shōwa Shin-zan (昭和新山).