Papua New Guinea has also had its share of rioting, most recently in Lae, the country's second-largest city, when marauding youths left nine people dead.

ECONOMIST: Ping-pong politics roil three island nations

Back at Ko Hong, just around the corner from Ao Bo Lae, the otherwise continuous circle of limestone cliffs that surround the island opens up slightly.

BBC: The perfect trip: Thailand

More than 20 field projects followed, on such themes as energy flows and recycling in Lae (Papua New Guinea), urban flora and fauna in Berlin (Germany) and in Xalapa (Mexico), children in the city of Toronto (Canada), urban green spaces in Dayton (USA), Seoul (Rep. Korea) and Valencia (Spain) and linkages between the urban and rural environments in Bangkok (Thailand) and Rome (Italy).

UNESCO: Urban connections of biosphere reserves