Hokkaido Mountain Passes

Southern HokkaidoRoute 227

Oshima-Nakayama Pass353 m

Hokuto City, Hokkaido ・ 渡島中山峠（おしまなかやまとうげ）

Around Oshima-Nakayama Pass3D view built from GSI elevation data and recent aerial imagery. The orange line is Route 227 (white dashes are tunnels). Use the buttons at top left to view from the north, east, south or west, or drag to rotate. On phones, move two fingers up or down to tilt, and pinch to zoom.

Loading the terrain

GSI Tiles (elevation tiles, seamless aerial photos), processed by this site. Road lines: © OpenStreetMap contributors.

Check if the road is open

Closures and road conditions change by the hour. Check official road information before you set off. These sites are in Japanese; your browser's translation feature helps.

Pass data

Elevation
353 m#22 of 31 by heightFrom Kita-no-Michi Navi mountain pass information (Civil Engineering Research Institute for Cold Region).
Road
National Route 227
Location
Hokuto City, HokkaidoMunicipalities of the pass and within 300 m of it (GSI reverse geocoder).
Length of the pass section
16 kmBetween the chain-up areas (or road gates) on each side
Steepest grade
6.4%Rises or falls 6.4 m over 100 m
Tightest curve
123.6 m radiusMinimum curve radius; smaller is sharper
Road width
6.5 m
Chain-up areas
Hokuto side: yes / Assabu side: yes
Preventive closure in heavy snow
No

Section length, grade, curve, width and chain-up areas are from Kita-no-Michi Navi mountain pass information (Civil Engineering Research Institute for Cold Region) (in Japanese), which is based on a 2001 road handbook, so some details may have changed. GSI Maps has no label for this pass, so it is placed at the highest point of the road within the preventive closure section. Checked: 2026-11-03

Open in GSI Maps

This page is not a driving guide. In winter, weather and road surfaces on mountain passes change quickly. Check the latest road and weather information, and do not push on in bad conditions.

Weather at Oshima-Nakayama Pass

Sunrise and sunset

SUNRISE--:--
SUNSET--:--

Today's times (Japan time) calculated for the pass's latitude and longitude against a sea-level horizon. Surrounded by mountains, the pass gets sunlight later and loses it earlier than these times.

Japan Meteorological Agency pages

Nearby passes

Nearby roadside stations

Nearby mountains

Nearby lakes

Straight-line distances from the pass.