TOUGH SLOG: Shooting Sports Illustrated’s swimsuit issue isn’t just a romp on the beach. The SI team and the intrepid models last year covered some icy terrain in Antarctica, persevered through sandstorms in Africa and traversed treacherous cliffs in Asia, according to SI and the Travel Channel, which will air a special on the making of the swimsuit campaign on Sunday, 8 p.m. Eastern time. “The journey to all seven continents was a bold undertaking…” said Mark Ford, president of the Time Inc. Sports Group, in a statement. He said the special will show “a completely new and captivating perspective of the swimsuit franchise.” Laureen Ong, president of the Travel Channel, said, “This is not an hour of just models posing on sandy beaches. This special takes viewers to all seven continents, spotlighting the most magnificent places in the world.” Since the SI swimsuit issue debuted in 1964, the franchise has become a marketing phenomena, extending to consumer products, as well as digital, social, broadcast, print and mobile media. Kate Upton, in a bikini and ski parka, is for the second year in a row on the cover of the issue, which comes out this week.