Unkai Terrace is a mountaintop observation deck located at the Hoshino Resorts Tomamu complex in Shimukappu, Hokkaido, Japan. Situated at an elevation of 1,088 meters on Mount Tomamu, the terrace was opened in 2005 as a premium viewing platform designed specifically for witnessing the phenomenon of unkai, which translates to "sea of clouds." The facility was developed to take advantage of the region's unique meteorological conditions that create spectacular cloud formations in the valleys below.
The terrace's significance lies in its position as one of Japan's most reliable locations for observing unkai, a natural phenomenon where low-lying clouds settle in mountain valleys and basins, creating the visual effect of an ocean of clouds. This occurs when temperature inversions trap moisture near the ground while the peaks remain clear. The Tomamu area experiences particularly favorable conditions for unkai formation during the early morning hours from spring through autumn, with the highest probability occurring between May and October. The phenomenon holds cultural resonance in Japanese aesthetics, embodying concepts of transience and natural beauty.
Visitors access the terrace via a 13-minute gondola ride that departs from the base of the resort. The gondola operates during designated seasons, typically from late May through mid-October, with early morning departures beginning before sunrise to coincide with optimal viewing conditions. The terrace itself features multiple observation decks at different levels, including the Cloud Walk, a raised platform extending outward from the mountainside, and the Cloud Pool, a reflective water feature designed to mirror the sky and clouds. Additional platforms such as the Cloud Bed provide cushioned seating areas where visitors can recline while watching the cloud formations shift and dissipate with the rising sun.
The site is located approximately 90 minutes by car from New Chitose Airport and about 100 kilometers southeast of Sapporo. Visitors can reach Tomamu Station via JR Sekisho Line from Sapporo, with the journey taking roughly 90 minutes, followed by a short shuttle bus or taxi ride to the resort. Gondola tickets are sold separately from resort accommodations, and prices vary depending on whether guests are staying at Hoshino Resorts properties or visiting as day guests. The experience is weather-dependent, and successful unkai sightings occur on approximately 40% of operating days, with no guarantees or refunds based on cloud conditions.
