An Ebola epidemic thundering through heavily populated provinces in the northeastern Democratic Republic of the Congo has sickened more than 110 people in the past week—despite the efforts of specialist medical teams, an effective vaccine, and new treatments that are being tested in the region. The outbreak already is the second-largest on record, behind the…

This article was created in partnership with the National Geographic Society. After a month of sailing the great Southern Ocean, during which there was a nine-day medical evacuation, after a few days digging ditches on a remote island chain searching for ancient penguin bones, after the sea sickness medications and the seal tagging, the test…