The best sunglasses for hiking: altitude changes the answer

For hiking below the treeline, a brown polarized lens is the right choice: it lifts contrast so roots, rocks and the line of the trail read clearly through the changing light under trees. Above the treeline the answer changes. Ultraviolet rises by roughly ten percent for every thousand metres of altitude, pale rock and snow reflect a large share of it back up, and the light is harder and flatter. Up there you want a darker lens, a UV claim you trust, and a frame that covers the sides. On snow, that becomes a matter of injury, not comfort.

Below the treeline: contrast

Forest and lower trails are a contrast problem. Light comes through leaves in patches, the ground is a mix of shade and sun, and what you need to see is texture: a root across the path, a wet rock, the edge of a drop. A brown lens absorbs more blue than a grey one, which strips haze and separates near from far. The trail reads better. That is the T01 Brown.

Keep it medium rather than dark. You pass through deep shade, and a dark lens turns it black. Our lens colour guide explains the trade between contrast and true colour.

Polarized helps here less than on water, because there are few flat reflective surfaces, but it costs nothing and it earns its keep the moment the trail crosses a stream or a wet slab.

Above the treeline: UV and glare

Three things change once you climb out of the trees.

UV increases with altitude. The atmosphere absorbs ultraviolet, and there is less of it above you the higher you go. The figure most bodies quote is about ten percent more UV per thousand metres. At three thousand metres you are in roughly a third more UV than at sea level.

The ground reflects it back. Pale rock, sand and especially snow bounce UV upward, so it reaches your eyes from below as well as above. Snow reflects up to about eighty percent. A lens that only shields from the front leaves the sides and the bottom open.

The light is harder. Thinner air scatters less, so shadows are sharper, the sky is darker and the sun is more intense. The medium lens that was right in the forest is too light.

So above the treeline: a darker tint, or a mirror over a dark base, a frame that sits close or has side coverage, a hat with a brim, and a UV claim you have reason to believe. The Grey is the neutral choice for high open terrain in bright sun; the Ice Blue Mirror is the one for snow.

On snow: an injury, not a comfort question

Snow blindness is a sunburn of the cornea. It comes from a few hours of unprotected UV exposure on bright snow, it is painful, and it takes a day or two to recover. It is entirely preventable with lenses that block UV and cover the eye, which is what glacier glasses are: dark lenses with side shields. Our snow blindness post covers the symptoms and the prevention.

For a day on a snowfield, a dark mirrored lens and a frame that covers the sides is the minimum. For glacier travel or high altitude, proper glacier glasses or goggles.

What the UV claim needs to be

At sea level in town, the difference between "UV protection" and "UV400" is small in practice. On a mountain, with more UV arriving from more directions for more hours, it matters. Our UV400 vs polarized post explains what each label means.

Our lenses are listed by the frame maker as "UV protection coating" with no cut-off wavelength stated, and we say exactly that on every product page rather than upgrade it. For low and mid-altitude hiking that is a fair claim. For high altitude and snow, ask any seller for UV400 in writing, and consider a pair built for it.

Fit on the trail

A frame that slips on a descent or fogs on a climb is a nuisance for hours. A light plastic frame that sits without clamping, and that lets air behind the lens, is the one to carry. Our fogging post explains the summit fog problem. A retainer cord is worth its weight on any hike with scrambling.

Frequently asked questions