Gavin Hellier / Iguacu Falls, Foz do Igua?u, Iguacu (Iguazu) National Park, Brazil, South AmericaSeptember 2016. Hellier

Ingo Arndt / Sunrise at Iguacu Falls, largest waterfalls in the world, Iguacu National Park, Brazil

Nick Garbutt,Nick Garbutt / Tourist watching masses of butterflies drinking from temporary pools. Various species including Large Orange Sulphur (Phoebis agarithe), Cloudless Sulphur (Phoebis sennae), White-angled Sulphur (Anteo...

Nick Garbutt / Iguasu Falls by moonlight, on the Iguasu River, Brazil / Argentina border. Photographed from the Brazilian side of the Falls. State of Parana, Brazil.

Ben Lascelles / Great Dusky Swift (Cypseloides senex) Birds flying past rainbow created by waterfalls, Iguazu National Park, Argentina, October 2008

Ben Lascelles / Iguazu waterfalls, Iguacu National Park, Argentina. October 2008.

Michael Hutchinson / Waterfalls, Iguacu (Iguazu) National Park, Brazil

Thomas Marent / Cascades of the Iguacu Falls, the world's largest waterfalls, Iguacu National Park, Argentina

Thomas Marent / Two Sisters Waterfalls, Iguacu Falls National Park, Brazil

Thomas Mangelsen / Cascades of Iguacu Falls surrounded by tropical rainforest, Iguacu Falls National Park, Brazil

Konrad Wothe / Rainbow at Iguacu Falls, largest waterfalls in the world, Iguacu National Park, Brazil

Luke Massey / Great dusky swifts (Cypseloides senex) roosting behind one of the falls at Iguassu Falls, Brazil