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COVER: ALEX TAIT/NATIONAL GEOGRAPHIC STAFF. TOC: (BACKGROUND) KERTU_EE/ISTOCK/GETTY IMAGES PLUS; (EVEREST VIDEO) CAMP4 COLLECTIVE/IMAGE BANK FILM/GETTY IMAGES; (ESCAPE ON THE PEARL) ADAM TURNER; (RIVER OF ICE) ÞORVARÐUR ÁRNASON. EXPEDITION EVEREST: (EVEREST VIDEO) CAMP4 COLLECTIVE/IMAGE BANK FILM/GETTY IMAGES; (ALEX TAIT INSET) CHRISMILLBERN; (ROPE) MARIUSZ SZCZYGIEI/SHUTTERSTOCK; (CARABINER) MOUNTAIN CUBS/SHUTTERSTOCK; (AIRPORT) VOJTECH FLIDR/SHUTTERSTOCK; (WORLD MAP) MAPPING SPECIALISTS, LTD; (INSET MAP) KPG_PAYLESS/SHUTTERSTOCK; (GLACIER WATER VIDEO) SERGEYXSP/CREATAS VIDEO+/GETTY IMAGES PLUS; (ALEX AND SHERPA) BRITTANY MUMMA; (SHERPA GROUP) AMRIT ALE; (CLIMPING VIDEO) ALEX TAIT/NATIONAL GEOGRAPHIC STAFF; (CLIMBING PHOTO) ALEX TAIT/NATIONAL GEOGRAPHIC STAFF; (DRONE) VALENTIN VALKOV/SHUTTERSTOCK; (MAPPING DEVICE) DIRK COLLINS/NATIONAL GEOGRAPHIC IMAGE COLLECTION; (BASECAMP VIDEO) CHRIS MILLBERN; (ICE CORE VIDEO) ALEX TAIT/NATIONAL GEOGRAPHIC STAFF; (WEATHER STATION) ALEX TAIT/NATIONAL GEOGRAPHIC STAFF; (SCIENCE AND EXPLORATION BACKGROUND) SKAMAN306/MOMENT/GETTY IMAGES. LIFE AT THE EXTREMES: (HANDS AND GLOBE) INCOMIBLE/SHUTTERSTOCK. FIVE FACTS ABOUT MOUNT EVEREST: ARSGERA/SHUTTERSTOCK. ESCAPE ON THE PEARL: (ALL ILLUSTRATIONS & MAP) ADAM TURNER; (BOOK) NGS STAFF; (AUTHOR) IRENE OWSLEY. RIVER OF ICE: (BIG PHOTO) ÞORVARÐUR ÁRNASON; (M JACKSON INSET) JAMES BERNAL; (M JACKSON VIDEOS—ALL) NATIONAL GEOGRAPHIC STORYTELLING; (SKAGWAY AIRPORT) DESIGN PICS INC/ALAMY STOCK PHOTO; (HOFFELLSJOKULL GLACIER) ÞORVARÐUR ÁRNASON; (HOW A GLACIER FORMS) NGS STAFF; (CREVASSE) CAVAN/ALAMY STOCK PHOTO; (SERACS) RYAN VOLUM/NPS/SCIENCE SOURCE; (M JACKSON TAKING PICTURE) JOE TIGHE; (TIDEWATER GLACIER) BRYAN AND CHERRY ALEXANDER/SCIENCE SOURCE; (VALLEY GLACIER) ÞORVARÐUR ÁRNASON; (PIEDMONT GLACIER) DR JUERG ALEAN/SCIENCE SOURCE; (ICE CAVE) STEPHAN MANTLER; (MUIR GLACIER BEFORE) WILLIAM O. FIELD/NASA; (MUIR GLACIER AFTER) BRUCE F. MOLNIA/NASA; (LIFE AT THE EXTREMES) JOE TIGHE. ICY VOCAB: JAMES BERNAL. THE END: WEAVER1234/ISTOCK/GETTY IMAGES PLUS.