The Subway slot canyon in Zion National Park, Utah, USA

© Stan Moniz/Tandem Stills + Motio

The end of the line. Zion National Park, Utah, USA

Zion National Park in the US state of Utah is known for its steep red cliffs, maze of sandstone canyons and waterfalls with colourful hanging gardens. Visitors here can trek for miles, resting in canyons once occupied by the Ancestral Puebloans, an ancient Native American culture that spanned parts of the south-west USA.

The bravest souls might venture into Zion’s Subway. Yes, there’s a ‘subway’ here, but it’s not an underground railway nor a sandwich shop. You see the image we are featuring today? That’s the Subway. It’s a geological marvel, a hollowed-out canyon reminiscent of a Tube tunnel. To get here requires some technical experience, or at least a guide. There will be bouldering, climbing down waterfalls, possibly abseiling and a 9-mile hike on a trail which is a running stream with parts so deep, hikers have to wade or swim, depending on water levels. Did we mention it’s cold too?

All that work is worth it in the end for a photo like this. Zion celebrates its 102nd anniversary today and is the third most-visited national park in the USA, but just 60 permits a day are granted to hikers who want to attempt a visit to the Subway slot canyon.