How long does the Mountain Track take?

Six to eight hours for a fit walker in summer, and longer in winter or in poor visibility.

Is the cache reachable in winter?

It can be, but it is often buried under drifted snow and the summit in winter is not a place to be searching walls. Attempt it between June and September.

What is the difficulty rating about?

Partly the search — the ruin is large and the stones are unremarkable — and partly the fact that the container is not at the obvious landmark.

GC8Z1QM · Traditional · placed 28 May 2016

The Observatory Ruin

56.7970, -5.0040 Scottish Highlands, Lochaber

Difficulty4
Terrain5
ContainerSmall
KindTraditional

A cache at the ruins of a Victorian weather observatory on the summit of Ben Nevis, where men lived for twenty years to record the worst weather in Britain and where the records they kept still matter.

Published 24 October 2026By The Wayfinding Desk

A pin plate: a compass rose head with engraved marks and a needle set to this cache bearing. — Bearing 49°, 40 engraved marks, 2 ring(s).

The building you are looking for

The ruins on the summit plateau are the remains of a meteorological observatory that operated from 1883 to 1904. For twenty-one years a small staff lived up here continuously, taking readings every hour, day and night, in conditions that most people experience once and remember for a lifetime.

The observatory was a substantial building: a two-storey tower, a laboratory, living quarters, and a walled enclosure to keep the instruments from blowing away. It was abandoned when the grant funding ran out, and the summit hotel that had grown up alongside it closed shortly afterwards. The stone was stripped and reused; what remains is the lower courses and the west gable, which stands about three metres.

Why the records matter

The Ben Nevis observations are the first long continuous high-altitude weather record in Britain, and they are still used. Among other things, they established:

Finding	Value
Highest wind speed recorded during the observatory years	Over 140 mph, in January 1888
Days per year with gale-force wind	About 260
Days per year with clear summit visibility	About 70
Mean annual temperature at the summit	Roughly 3 degrees Celsius lower than at Fort William below
Deepest level snow measured at the summit	Several metres, drifting far deeper in gullies

The observatory staff also measured the snowfall record that stood for a century, and their hourly pressure readings are used in modern reanalysis work because they are consistent, calibrated and unbroken.

The find itself

The cache is not at the summit cairn, which is the most visited and most dug-over square metre in Scotland. It is on the west gable of the ruin, at the base of the wall where it meets the old path line, under two flat stones that sit flush with the surrounding rubble.

Lift the two stones together and the container is in the shallow hollow beneath. It is a small clip-lock with a logbook and a pencil. There are no swaps: nothing survives freezing and thawing repeatedly, and the container is small.

Replace the stones so the wall base reads as it did. The ruin is a scheduled monument and the summit plateau is a Site of Special Scientific Interest.

Terrain and safety

This is a serious mountain in any season, and the terrain rating of five is not an exaggeration.

The Mountain Track from Glen Nevis is the easiest route and still involves 1,340 metres of ascent over about eight kilometres of rough, eroded and partly stepped ground.
Snow lies on the summit plateau from November into May in most years, and patches persist into July in gullies. In winter the track becomes a snow climb and the upper section is avalanche terrain.
Navigation on the plateau in cloud is genuinely difficult. The summit is a boulder field with steep drops on the north side, and the north face corries take lives most years.
Take a map, a compass, waterproofs, an extra layer, food and a torch. Tell someone your route and expected return time.
The summit has no shelter except the ruin, which does not have a roof. Do not rely on it.

After the find

The Carn Mor Dearg arête on the north side is one of the finest ridge walks in Britain and gives a view of the north face that most summit visitors never see. It requires a head for exposure and a full day.

Trails in reach

Mountain Track from Glen Nevis
Carn Mor Dearg arête
North Face approaches

Questions

How long does the Mountain Track take?: Six to eight hours for a fit walker in summer, and longer in winter or in poor visibility.
Is the cache reachable in winter?: It can be, but it is often buried under drifted snow and the summit in winter is not a place to be searching walls. Attempt it between June and September.
What is the difficulty rating about?: Partly the search — the ruin is large and the stones are unremarkable — and partly the fact that the container is not at the obvious landmark.

Maintenance record

Every change made to this cache since it was placed, as recorded by the owner.

2 June 2026Verified. Wall stable; two flat stones still in place.
20 August 2022Container replaced after UV damage to the lid. Same position.
16 February 2019Found under a foot of snow, intact. Logbook replaced in June.
28 May 2016Placed. Small clip-lock, logbook, pencil. No swaps above 1,000 metres.