Because there used to be some doubt as to which of Ruapehu's peaks was the highest, several early explorers claimed to have been first to reach the summit. The position was further complicated because the mountain was sacred to the Maoris and climbers had to conceal the evidence of their attempts from Te Heuheu and the Taupo tribes. In the late 1840s Sir George Grey and the Rev. Richard Taylor climbed some distance up the mountain, and on 30 January 1853 they explored the eastern slopes and appear to have reached the summit icefield. On 12 December 1877 John and Thomas Allison, of Wanganui, climbed to the summit of Te Heuheu Peak (9,040 ft). They were followed, in February 1879, by G. Beetham and J. P. Maxwell, who discovered the crater lake but did not approach closely enough to find that its waters were warm. The first ascent of Paretetaitonga (9,025 ft) was accomplished in 1882 by H. C. Field, a civil engineer from Wanganui. It was left to James Park, C. Dalin, and W. H. Dunnage to ascend Tahurangi (9,175 ft) to the true summit of Ruapehu. On 8 January 1886 this party climbed Girdlestone Peak (8,670 ft) believing that they would then find a quick route to the top of Tahurangi. They were disappointed in this and had to retrace their path with some difficulty before they could make their successful attempt on Tahurangi.