Roughing it? Not exactly. Spend three days and two nights afloat and on foot deep in the canyons of the Colorado River, feasting under the stars and losing yourself in the string wizardry of Jay Campbell, cello, and Francisco Fullana, violin. Bach is on the playlist, as are contemporary composers and who knows what else. Specific repertoire will be announced, as the parlance is, “from the stage—a stage in this case being a scenically breathtaking, acoustically singular natural backdrop carved over eons by the elements, and the elements alone. No previous camping experience required. But how on earth will the players transport their instruments? —M.G.