mathias has watched the biggest city explode, stretching the limits of water, power and sanitation. ♪an extra 3 billion or 4 billion people living on this planet. do you think it's possible to preserve what's left of this garden of eden with that kind of pressure? can we have it both ways? >> we cannot give it away, the thought that we can still do it. with 3 billion people more, the task will be harder. we'll do our best. >> the man in charge of the park knows that without tourists there would be no park. but too many people could turn galapagos into another hawaii where 95% of native species were wiped out by too much change, too fast. so he is proposing a cap of less than 25,000 visitors per year. >> the way tourism is going up, we will probably reach by 2016 that limit. >> but he says galapagos can only thrive with the right kind of visitor, the eco tourist, willing to play top dollar to see a blue-footed booby but not demand a golf course and water park as part of the package. he wants strict movement on human movement, visitors like paul. >> they put those stakes there in 1944 t