Ingo Arndt / Tourists on viewing platform, Iguacu Falls, Iguacu National Park, Brazil

Alex Mustard / People watch Sockeye salmon (Oncorhynchus nerka) migration from a viewing platform over Adams River. Part of the eco-tourism associated with the salmon run. Adams River, British Columbia, Canada, Octo...

Merryn Thomas / Viewing platform on the summit of the Schilthorn (2,970m), Bernese Oberland, Switzerland, June 2012.

Franco Banfi / Piraputanga (Brycon hilarii) in the main spring with people standing on nearby viewing platform, Aqua¡rio Natural that goes in the Rio Bai­a Bonita, Bonito, Mato Grosso do Sul, Brazil

Franco Banfi / Piraputanga (Brycon hilarii) in the main spring with people standing on nearby viewing platform, Aqua¡rio Natural that goes in the Rio Bai­a Bonita, Bonito, Mato Grosso do Sul, Brazil

Franco Banfi / Tourist on viewing platform in Punta Cantor, Peninsula Valdes, Chubut, Patagonia, Argentina, Atlantic Ocean, October

Mark MacEwen / Forest elephants (Loxodonta cyclotis) in Dzanga Bai Clearing, with wooden viewing platform, Central African Republic, Africa.

Enrique Lopez-Tapia / Wildlife viewing platform, with chital deer (Axis axis) in the distance, Sundarbans National Park, the largest mangrove swamp in the world. Bangladesh. UNESCO World Heritage Site. June 2012.

Shattil & Rozinski / Tourists on boardwalk viewing platform watching salmon spawning along a stream and waterfall in Ketchikan, Alaska, USA. September 2010. A fish ladder to the side of the stream creates an easier route...

Michael Hutchinson / Tourists on viewing platform dwarfed by Iguazu falls including Garganta del Diablo (Devil's throat), Iguacu National Park, Argentina February 2009

Michael Hutchinson / People on viewing platform dwarfed by Iguazu falls, Iguacu National Park, Argentina February 2009

Michael Hutchinson / Man on viewing platform watching the Iguazu waterfall, Iguaçu National Park, Brazil