written by Cathy Carroll IN A DOME built into a hillside, a round skylight at its crown, Burdoin Mountain rising behind it and the Columbia River flowing in the foreground, the yoga session began. The poses unfolded easily for the participants, who’d spent the night steps away in a ring of cabins inspired by minimalist Japanese design, and the morning rotating between the sauna, the cold plunge pool, the warm saltwater soaking pool and the hot tub outside, gazing up at the Zen landscape—the Gorge veiled in mist. Yoga at the subterranean Sanctuary at The Society Hotel in Bingen, as with other retreats, just isn’t the same as hitting the nearby studio after work. Done anywhere, yoga can calm the spirit while strengthening the body, but retreats can amplify the experience as well as the benefits. This spring, yoga retreats throughout Washington offer varying themes, from hiking and uncovering your…