Imax 3D nature documentary “To the Arctic” has been running an impressive marathon.After almost 30 weeks in domestic Imax theaters, the 3D film, from MacGillivray Freeman Films, Imax and Warner Bros., crossed the $10 million worldwide benchmark to hit $11.8 million — in line to become the highest-grossing documentary created for Imax this year. “To the Arctic” debuted April 20 domestically at 50 Imax locations, and has since expanded to roughly 75 worldwide, including 22 international theaters. The pic bowed Oct. 18 in Russia. “The film provides audiences that immersive, you-are-there experience that built the giantscreen industry, and keeps our audiences coming back for more,” says director Greg MacGillivray, who released the film under the One World, One Ocean campaign — a 10-year multiplatform media initiative designed to change the way people see and value the world’s oceans. “To the Arctic,” which collected this year’s top prizes at the Giant Screen Cinema Assn. Achievement Awards, centers on a mother polar bear and her twin cubs as they struggle to navigate the changing Arctic environment. Meryl Streep narrates, with original songs by Paul McCartney. Up next for MacGillivray is “Hidden Universe,” slated to bow in March via December Media.