TERRA INCOGNITA

With the mission to Mars and commercial space travel taking over headlines in recent years, we turn the spotlight back to Earth with these reminders of how sublime - and alien - our own planet can be.

- JEFF YEUNG

VATNAJÖKULL GLACIER
ICELAND

Aside from the jet-black volcanic sand of Reynisfjara beach, Iceland is home to another geological marvel reminiscent of an alien planet: the Vatnajökull glacier. The second largest of its kind in Europe, the glacier covers 8,100 sq km - roughly eight per cent of the country's landmass - and runs as deep as 900m. While its surface structure is enough to amaze even the most-travelled explorer, it's even more stunning when you delve deep into its myriad ice caves, a number of which are now easily accessible via guided tours.

Unfortunately, much like our planet's many other ice caps, climate change has gradually eroded the glacier. Over the past 15 years, its average thickness has decreased by almost a metre a year, and ever-warming temperatures are only exacerbating the melting. The Vatnajökull glacier also masks a number of active volcanoes, including Öræfajökull, Grímsvötn and Bárðarbunga- and though eruptions in the region have been rare in recent years, geologists believe we'll be seeing more volcanic activity in the next 50 years.

LENCOIS MARANHENSES NATIONAL PARK
BRAZIL

Sand dunes may be nothing unusual to the well-travelled, but the view of Brazil's Lencois Maranhenses National Park is out of this world with its cobalt-and-verdant freshwater lagoons nestled among the dunes that stretch more than 70km along the coast and up to 50km inland. Rainwater fills these pools from May to September every year, and an impermeable rock surface beneath the dunes prevents the crystal-clear water from draining.