The local Tlingit community has called it “Sumdum” for generations, in reference to the thundering echo of ice calving off glacier fronts into the deep fjords. A nearby mine produced nearly half a million dollars in gold and silver over a decade of operations before closing in 1903. John Muir, exploring by canoe in 1880, offered nuanced and impassioned descriptions of this “Yosemite of the North,” fueling scientific voyages to Alaska and, posthumously, the wilderness preservation movement. This is Tracy Arm-Fords Terror Wilderness, approximately 50 miles southeast of Juneau and the site of today’s expedition activities.

Our morning featured a 25-mile, awe-inspiring transit down Tracy Arm fjord, surrounded by steep granite, gneiss, and schist walls less than a mile apart and rising to elevations of 2,000 feet or more. We stopped for photo opportunities at numerous waterfalls and proceeded slowly through accumulations of bold, blue icebergs and smaller growlers. The fjord, 1,242 feet at the deepest, formed as Sawyer and South Sawyer glaciers together advanced and retreated many times over the past several million years, reaching their most recent maximum positions around 1750. Both glaciers in Tracy Arm are presently receding.

South Sawyer Glacier, destination for our afternoon tour, is a tidewater glacier in direct contact with the ocean. As the tides of southeast Alaska rise and fall, sometimes experiencing more than 20 vertical feet of change, the fluctuating water level stimulates the floating edge to calve off large chunks of ice, often in dramatic fashion. Using National Geographic Sea Bird expedition landing crafts, we ventured among the multitudes of icebergs, harbor seals, and bergy bits seeking the best views of the glacier face. Calving episodes interspersed with moments of a silence only possible deep in the wilderness left powerful impressions. The brilliant aquamarine hues, intricate natural ice sculptures, and difficult-to-comprehend scale of the fjord and glacier together were spectacular! A determined and daring few capped off this wonderful day with a polar plunge, swimming alongside icebergs in true Alaskan fashion.