Shane P. White / Rainbow over waterfall, Iguacu Falls, Brazil

Shane P. White / Bosetti Waterfall, Iguacu Falls, Argentina

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...

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

Kevin Schafer / Iguacu Falls, world's largest waterfalls, Brazil and Argentina border

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

Luiz Claudio Marigo / Iguassu Falls, Iguassu NP, border of Brazil and Argentina

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

Michael & Patricia Fogden / Iguacu falls as seen from the Brazilian side, Brazil and Argentina border