Iceland
Read MoreThese stone cairns mark the trail above the snow line between Landmannalaugar and Hrafntinnusker.
They seem close together, but the day after this photo was taken, we were forced to navigate in dense fog by moving from one marker to the next.
One of these cairns has a plaque on it commemorating a young hiker who died in a blizzard near here on June 27, 2004 - hardly the middle of winter.One of Iceland's most dangerous volcanoes is Katla (4 eruptions since 1947). When Katla erupts, the resulting jökulhlaup starts here - at Emstrur.
The Emstrur huts are located at the mouth of an amazing gorge carved by many centuries of jokulhaups.
When volcanic activity is detected at Katla, the wardens begin shooting off flares and sounding alarms (sirens and flash-bangs). When you hear those alarms, you get to high ground as fast as you can - no delay.