. >> matt larsen is used to the ships. he's the director of the smithsonian tropical research institute here. he loves to point out the incredible diversity in panama. for scientists, this is a dream location. >> what makes panama a unique place to study the environment? this is a remarkable place. because we have a very narrow ismis here- 50 mi at the narrowest point so we can get to either ocean the pacific or the atlantic in a matter of an hour. >> we spoke with matt at the smithsonian's nature center at culebra point, a narrow strip of land that juts straight into the ocean. ships were passing by, the sun was heading down for the night. it was time to get down to business. >> i understand there are sloths here? >> yes. >> can we go take a look? >> yes, let's go take a look they are very handsome. >> turns out sloths aren't the most outgoing animals. we had a bit of scanning of treetops to do. and then, we saw our first signs of life. >> there's one. oh yeah. oh there's another sloth right there. >> he's just mooning yo