Hamill has guided 72 expeditions to altitudes exceeding 18,000 vertical feet, including 5 on Mt. Everest and 18 in the Himalayas above 8,000m (26,000 ft) (Everest: spring, 2005; spring, 2008; spring, 2009; spring, 2010; spring, 2011; spring, 2012; spring, 2013: Cho Oyu: autumn, 2002; autumn, 2003; autumn, 2004; autumn, 2005; autumn, 2007; autumn, 2008; autumn, 2010; autumn, 2011: Shishapangma: autumn, 2011: Manaslu: autumn, 2012).
Having trekked to Mount Everest base camp and reached the summits of a number of notable mountains, including two of the world's fourteen 8,000 meter peaks (Shishapangma and Cho Oyu), she decided to build on her passion for mountaineering and set herself the challenge of achieving the Explorer's Grand Slam.