What you can see on the Mount Esan cams
Esan is a volcano to watch from the inside: a crater basin ringed by grey, bare rock, where sulphur fumaroles stain the ground yellow and send steam drifting across it. On cold mornings the vapour is at its thickest; on warm afternoons it thins, and the colours of the rock and deposits come through instead. From further off, the rounded summit shows whether the headland is clear, under cloud or lost in sea fog.
Inside the crater basin, facing the morning sun
The camera stands on the floor of Mount Esan's crater basin and looks across it to the wall that encloses it. Low scrub and stony ground fill the foreground; behind, a long ridge of grey, bare rock curves across the frame from left to right and dips to a gap on the right-hand side. This is the basin where Esan's sulphur fumaroles vent, staining the ground yellow and sending steam drifting across it.
The camera faces roughly towards the morning sun, so early in the day the wall is in shadow and the sun can flare straight into the lens. Later, with the light behind the camera, the colours of the rock and the deposits come through.
Mount Esan's summit on the skyline
Where the crater camera puts you among the fumaroles, this one steps well back. The Japanese label names Takadai, and from there the rounded summit of Mount Esan rises along the bottom of the frame, with a pale patch near its top and a lower, darker ridge to its left. Above it is a wide stretch of open sky.
With the mountain taking up only the lower edge of the picture, this is a view for the weather over the headland rather than for detail. It shows at a glance whether the summit is clear, under cloud or lost in the sea fog that rolls in from the Pacific in early summer.
A volcano without a recent eruption
Esan last erupted in 1874, and the activity since has been limited to the fumaroles and the hot springs around the base. That makes it unusual among the volcanoes watched here: what the cameras show is not the run-up to anything, but the steady state of a volcano quietly venting gas, year after year. The colour of the deposits changes slowly with rain and temperature.
When to watch Mount Esan
Japan is nine hours ahead of UTC. Cold, still mornings give the most steam; that means winter dawns, when the contrast between the white vapour and the dark rock is strongest. Sea fog rolls in from the Pacific in early summer and can cover the whole headland.
Around Mount Esan
The slopes below the crater are covered with azaleas that flower in late spring, and the town of Esan holds a festival for them. Hakodate, with its harbour and night view from Mount Hakodate, is under two hours away by road.
Visiting Mount Esan
A road climbs to a car park partway up, and from there a short trail reaches the crater rim in about an hour. Gas concentrations can rise near the vents and the marked route keeps clear of them; signs at the trailhead give the current situation.
