Mills Peak is part of the Darran Mountains where it is situated above Milford Sound in the Southland Region of the South Island.

It is set within Fiordland National Park which is part of the Te Wahipounamu UNESCO World Heritage Site.

[5] Prevailing westerly winds blow moist air from the Tasman Sea onto the mountains, where the air is forced upward by the mountains (orographic lift), causing moisture to drop in the form of rain or snow.

The months of December through February offer the most favourable weather for viewing or climbing this peak.

[6] The first ascent of the South Ridge was made in November 2013 by Paula Macfarlane, Reece McKenzie, and Stanley Mulvany.