Mount Fuji Crater: The Ohachi-meguri Trail, Volcanic Geology & Summit Rim Walk

What Is the Mount Fuji Crater?

The summit of Mt Fuji is not a single peak — it is the rim of a volcanic crater roughly 780 meters in diameter and 200-250 meters deep. This crater, known as Ōnaiin (大内院, literally "great inner sanctum"), is the caldera of Japan's tallest and most famous volcano. When you "reach the top," you are standing on the crater's edge, looking down into a bowl of volcanic rock and, depending on the season, patches of snow.

The crater has not erupted from its summit since long before the most recent volcanic event — the Hōei eruption of 1707, which opened a separate vent on the mountain's southeastern flank. The summit crater itself is quiet, though Mt Fuji remains classified as an active volcano. For more on the mountain's geological profile, see our complete Mt Fuji area guide.

For most climbers, the crater is the defining feature of the summit. You can peer into it from the trail junction where the Yoshida and Fujinomiya routes converge, or you can walk the full rim on the Ohachi-meguri trail. For an overview of everything else at the summit — shrines, the post office, facilities — see our guide to what awaits at the summit.

The Ohachi-meguri Trail: Circling the Rim

Trail Distance, Direction, and Timing

Ohachi-meguri (お鉢巡り) is the trail that circles the entire crater rim. According to the official Mt Fuji climbing map, the full circuit is approximately 3.8 km and takes 90 minutes to 2 hours to complete at altitude.

The recommended direction is clockwise. Walking clockwise means you ascend the steep Umanose (馬の背) ridge section rather than descending it — a much safer approach on this slippery stretch of loose sand over bedrock. Anti-clockwise forces you down Umanose, which many climbers find dangerous, particularly in wet or windy conditions.

The trail follows what was historically the sacred pilgrimage path of the Fujikō (富士講), Edo-period religious groups who worshipped Mt Fuji and circumambulated the summit crater as a devotional act. The eight peaks along the rim were said to represent lotus petals — the mountain's summit as Buddha's throne.

What You See Along the Way

The circuit passes through a landscape unlike anything else in Japan. On the inner side, the crater drops away steeply — a sheer volcanic bowl with exposed rock layers showing centuries of eruptions. On the outer side, depending on visibility, you see the Fuji Five Lakes, the Pacific coast, and on exceptional days, distant mountain ranges including the Japanese Alps.

Key landmarks along the way include Kengamine (the true summit), several small shrine structures, weather monitoring equipment, and the ruins of the old summit observatory. If you are timing your climb for summit sunrise, the eastern rim of the crater offers the most direct sunrise views.

The trail surface alternates between rocky sections, compacted volcanic gravel, and the sandy slopes near Kengamine. There are no railings or barriers at the crater edge in most sections — stay on the marked path, especially in fog or pre-dawn darkness.

Reaching Kengamine: Japan's Highest Point

Kengamine (剣ヶ峰, 3,776 m / 12,389 ft) is the highest point in Japan and sits on the western rim of the crater. A stone marker at the top is one of the most photographed spots on the mountain. According to the official Mt Fuji climbing site, this is the true summit of Mt Fuji.

From the Yoshida and Subashiri Trails

If you climbed the Yoshida (吉田) or Subashiri (須走) trail, Kengamine is on the opposite side of the crater from where you arrive. You will need to walk roughly half the Ohachi-meguri circuit to reach it — about 40-50 minutes from the Yoshida trail junction. Most climbers from these trails complete the full rim walk rather than retracing their steps. For details on the complete climbing guide for all four trails, see our companion article.

From the Fujinomiya Trail (Shortest Route)

The Fujinomiya (富士宮) trail arrives on the crater rim closest to Kengamine. From the Fujinomiya 10th station, the walk to Kengamine takes roughly 20 minutes, making this the fastest route to Japan's highest point. However, the final approach includes the Umanose ridge — even from this direction, the sandy slope requires careful footing.

Trail Conditions and When It Is Open

The Ohachi-meguri trail is only accessible during Mt Fuji's climbing season, which typically runs from early July to early September. Even within the official season, the trail may be temporarily closed due to remaining snow, strong winds, or dense fog. According to the official climbing site, opening dates for the rim trail vary from year to year depending on snowmelt conditions.

Early-season climbers (first two weeks of July) have the highest chance of encountering snow patches on the crater rim, particularly on the northern and western sections near Kengamine. Late-season climbers (September) face shorter daylight hours and increasing cold. Mid-August generally offers the most reliable conditions.

The trail is free to walk — there is no separate fee for Ohachi-meguri beyond the standard climbing permit. Toilets at the summit area cost ¥200-300 per use (coin operated). No food or water is available on the crater rim itself; the nearest facilities are at the trail junction areas. For details on summit weather and altitude conditions, check our companion guide.

Practical Tips for the Crater Rim Walk

The Umanose Ridge: The Trickiest Section

Umanose (馬の背, literally "horse's back") is the steep, sandy ridge section just below Kengamine on the Fujinomiya side. The surface is loose volcanic sand over hard bedrock, making it slippery in both directions. Going up is challenging; going down is genuinely dangerous, especially when wet.

Wear gloves for this section — many climbers use their hands for stability on the steeper parts. Trekking poles help, but they can slip on the bedrock beneath the sand. Take your time. The section lasts only about 10 minutes, but it has caused more injuries than any other part of the summit circuit.

What to Bring for the Summit Circuit

Most climbers doing Ohachi-meguri will have already packed for the full climb, but a few items matter especially for the crater rim:

• Wind protection: The rim is fully exposed. Even on calm days lower on the mountain, summit winds can be fierce. Bring a windproof outer layer.
• Gloves: Essential for the Umanose section, and useful for warmth at 3,700+ meters even in summer.
• Water: At least 500 ml for the circuit. No water sources are available on the rim trail.
• Headlamp: If you are starting the circuit before dawn (common for sunrise seekers), the trail is not lit.
• Camera: The views from the rim, especially at sunrise, are among the most dramatic in Japan.

There are no emergency shelters on the Ohachi-meguri trail. If weather deteriorates rapidly, the safest option is to return to the nearest trail junction and descend. Summit conditions can change within minutes.

Frequently Asked Questions