Isabella Bird visited the Sandwich Islands in 1871, when she was forty. Her letters home to her sister Henrietta have a remarkable freshness and spontaneity, and reveal the transformation of a Victorian invalid into a fearless horsewoman and enthusiastic mountain-climber, who thought nothing of riding for miles soaked with rain and fording terrifyingly swollen rivers. She undertook a thirteen-hour unaccompanied trek to the summit of the extinct volcano of Mauna Kea, revelling in the security with which she was able to travel and camp out without guides or companions. At the end of her stay she was able to make the perilous ascent to the summit of Mauna Loa, the largest volcano in the world, camping for the night on the edge of the crater, at nearly 14,000 feet.