Indeed. And not just survival. The voyage from Elephant Island to South Georgia (800 miles, in the Southern Ocean in an open row boat) is considered by many to be the most remarkable act of seamanship of all time.

And the crossing of Elephant Island by foot - a task never before and -very- seldom accomplished since.

While both relatively short accounts towards the end of the book, either would merit top-10 lists of remarkable achievements.

He didn't get to Antarctica on that voyage, much less achieve the expedition goals. But in truth he achieved an expedition that has resonated so much more.

I assume you are referring to "Endurance: Shackleton's Incredible Voyage" by Alfred Lansing. There is also a very good account in "The Endurance: Shackleton's Legendary Antarctic Expedition" by Caroline Alexander. Amazing tale of fortitude and integrity.

Regarding the journey across Elephant Island, that too was incredible. I note that there are tour companies providing opportunities to do this, though I haven't managed to do it yet.