by releasing 500 specially marked logs into the river at a prearranged time. His British boss Captain Henry Harman posted men on the Dihang-Brahmaputra to watch for their arrival. However, Kinthup was sold into slavery, escaped, and ended up employed at a monastery. On three leaves of absence he managed to craft the logs, send a letter from Lhasa with his new intended schedule, and send off the logs. Four years had passed. Unfortunately his note to alert the British got misdirected, his boss had left India, and nobody checked for the appearance of the logs. In 1913, Frederick Marshman Bailey and Henry Morshead launched an expedition into the gorge that finally confirmed that the Tsangpo was indeed the upper Brahmaputra. Frank Kingdon-Ward started an expedition in 1924 in hopes of finding a major waterfall explaining the difference in altitude between the Tsangpo and the Brahmaputra. It turned out that the gorge has a series of relatively steep sections. Among them was a waterfall he named "Rainbow Falls", not as big as he had hoped. The area was closed after China invaded Tibet and disputed the location of the border in the Sino-Indian War. The Chinese government resumed issuing permits in the 1990s. Since then the gorge has also been visited by kayakers. It has been called the "Everest of Rivers" because of the extreme conditions. The first attempt was made in 1993 by a Japanese group who lost one member on the river. In October 1998 an expedition sponsored by the National Geographic Society attempted to kayak the entire gorge. Troubled by unanticipated high water levels, it ended in tragedy when Doug Gordon was lost. In January–February 2002 an international group with Scott Lindgren, Steve Fisher, Mike Abbott, Allan Ellard, Dustin Knapp, and Johnnie and Willie Kern completed the first full descent of the upper Tsangpo gorge section. The largest waterfalls of the gorge (near Tsangpo Badong, Chinese: ) were visited in 1998, by a team consisting of Ken Storm, Hamid Sarder, Ian Baker and their Monpa guides. They estimated the height of the falls to be about . The falls and rest of the Pemako area are sacred to Tibetan Buddhists who had concealed them from outsiders including the Chinese authorities. In 2005 Chinese National Geography named them China's most beautiful waterfalls. There are two waterfalls in this section: Rainbow Falls (about high) at and Hidden Falls just