| Lake Utonai | |
|---|---|
| ウトナイ湖 (Japanese) | |
.jpg) Lake Utonai | |
  Lake Utonai | |
| Location | Tomakomai, Hokkaido, Japan |
| Coordinates | 42°41′56″N 141°42′40″E / 42.69889°N 141.71111°E |
| Type | Freshwater lake |
| Etymology | Ainu meaning "where small streams gather" |
| Basin countries | Japan |
| Surface area | 2.20 square kilometres (0.85 sq mi) |
| Average depth | 0.6 metres (2.0 ft) |
| Max. depth | 1.5 metres (4.9 ft) |
| Shore length1 | 9.5 kilometres (5.9 mi) |
| Surface elevation | 3 metres (9.8 ft) |
| 1 Shore length is not a well-defined measure. | |
| Designations | |
|---|---|
| Official name | Utonai-ko |
| Designated | 12 December 1991 |
| Reference no. | 539[1] |
Lake Utonai (ウトナイ湖, Utonai-ko) is a shallow freshwater lake in Tomakomai, Iburi Subprefecture, Hokkaidō, Japan. It is within the Lake Utonai Sanctuary, created in 1981 as the first bird sanctuary designated in Japan. It later became the fourth Ramsar site in Japan in 1989.
Other names include Kim-un-to, Kimke-to, Utnay-to, Utnay-tō, Utonai-numa, and Utsunai-numa.