british explorer ernest shackleton, a veteran of an launched his own attempt toco cross thinent from north to south in 1914. he set off with 27 other men in a ship called the endurance. but disaster struck before they even reached the continent. the endurance was trapped by the sea ice that encircles antarctica, forcing the men to>> t's one of these stories where you think the worst has happened, that nothing else can go wrong and then it does. >> brangham: katie murray is a polar historian, and expert on shackleton's endurance voyage. in tourist season, she works for the company, one ocean expeditions, giving lectures to visitors on board. we talked in the ship's movie she told us how shackleton became a legend, not for hisex oration, but simply by keeping his men alive after the endurance was crushed to pieces. stranded on the ice, they ran out of food and were eventually forced to eat their dogs. later they used small boats to navigate two death-defying ocean crossings, before finally landing at a remote whaling slstation on south georgiad. >> the shackleton endurance story isltim

. >> anthony: the conditions endured by the first british antarctic explorers like scott, and shackletond the lengths of time they endured them, are well, horrifying to imagine. they made their journeys in wooden ships, then man hauling equipment across glaciers, ice floes, mountains and frozen seas surviving on penguin meat when rations ran out. >> ryan: you might start to smell some sulfur. you smell it? >> anthony: yeah i smell that sulfur. what's our altitude now? >> ryan: 13, two. >> anthony: about 22 miles from mcmurdo is cape royds, where a penguin colony of about 2,000 breeding pairs live. marine ecologist, dr. david ainley, has been studying this colony for 20 years. >> anthony: so you're tagging the young ones? >> david: right. >> anthony: do you follow them through their entire life? i mean essentially -- >> david: yeah, this year we've got a bunch of individuals that are 20 years old. >> anthony: why penguins, what brought you to penguin initially? >> david: well this kind of penguin does everything with no secrets. if you ask the right question and you're creative enough the

falcon scott and roald amundsen, or perhaps the most famous antarctic adventure story: ernest shackleton's dramatic" endurance voyage" several yrs later. we talked to murray in theat ship's movie t: >> it's quite incredible actually that 100 years after the heroic age, just over 100 years since scott and the lar party died on their return fromn the south poleyou've got these great stories of endurance and suffering, we can now come to antarctica effectively for fun. >> brangham: this record number of tourists coming here has been growing steadily since the 1980's when just a few thousand made the trip every year. >> when the soviet union collapsed, the soviet fleet of ice-strengthened vessels became available and people realized they could actually charter those and bring those down. that was what started the whole rush in the 1990s. >> brangham: today, more and more tour companies are rolling out new fleets of luxury ships capable of navigating these icy waters. the arrival of more and more visitors to antarctica is also leading to concerns about their impact on this priecine ystem: >> an