For centuries, the Northwest Passage, the long-sought sea route connecting the Atlantic and Pacific Oceans through northern Canada, was a holy grail of Arctic exploration. Even now, sailing through it isn’t guaranteed. Mark Synnott, a National Geographic Explorer, writer, and adventurer, attempted to sail his own boat through the Northwest Passage to retrace the doomed 1845 expedition of British explorer Sir John Franklin. None of the Franklin expedition’s 129 men made it home, but what exactly happened remains a mystery.   For more information on this episode, visit natgeo.com/overheard. Want more? Get the inside scoop on Mark’s Northwest Passage voyage and see gorgeous photos in the August issue of National Geographic. Watch Explorer: Lost in the Arctic, premiering August 24 on National Geographic and streaming the next day on Disney+ and Hulu. And to go even deeper, Mark will tell the full story in his book Into the Ice, coming fall 2024 from Dutton, an imprint of Penguin Publishing Group. Also explore: On paper, Sir John Franklin’s expedition seemed to lack for little. There were ironclad ships, steam engines, libraries totaling 2,900 books, and even animal companions—two dogs and a monkey. Here’s how it all went wrong. Explore another polar expedition gone wrong—Shackleton’s expedition to Antarctica aboard Endurance—in the Overheard episode “What the Ice Gets, the Ice Keeps.” Learn more about your ad choices. Visit megaphone.fm/adchoices