The Uncanny X-Men, Vol. 3 (Marvel Masterworks);

The heart of an Antarctic volcano. The steamy jungles of the hidden Savage Land. Coastal Japan in flames and the far-flung Canadian city of Calgary buried in drifts of snow. All these locales and more await our merry band of mutants in the following eleven issues- and there's no time to catch your breath! This volume reads as one long story, setting the tone for the heavy continuity approach the next two decades would take. The first issue the X-Men wake up somewhere strange and by the end of the book, they still haven't gotten home!

Collecting:

X-Men #111-121