札幌 (Sapporo) is the main city of 北海道 (Hokkaido) island, and is famous for its annual 雪祭 (snow festival).
Access is possible from the main land by express train or by plane.
Travel tips: 札幌の雪祭 (pronounced Sapporo no yuki-matsuri, snow festival of Sapporo) is held every year in early February, and is worth the trip. However it is very popular, and prices of flights and hotels raise accordingly; I therefore recommend to go there on week days. The view from the top of 藻岩山 (pronounced moiwa-san, Mount Moiwa) is great, and in winter there is a bar completely made of ice and snow: the bar The Ice. The 豊平峡温泉 (pronounced Hoheikyo-onsen, Hoheikyo spa), an hour and a half from 札幌 (Sapporo) by bus, is a relaxing outside spa surrounded by the mountains; great when snow is all around.
Please check the photos of my visit in February 2007.