[1][2] Harris has worked on medical assistance teams in natural disasters in the Pacific region and taken part in Australian Aid missions to Vanuatu.

Harris's cave diving experiences include leading a team of Australian divers to record depths of 192, 221 and 245 m (210, 242 and 268 yd) in 2011, 2012, and 2020[3] whilst searching for the source of New Zealand's Pearse River: this mission was filmed for National Geographic.

At the 18 July press conference, it was revealed that the soccer team decided as a group that the boys who lived the farthest away should leave first, so they could ride their bikes home.

[9] To allow the rescue to occur, Harris developed a plan to keep the boys anaesthetised with ketamine while spontaneously breathing through full face masks.

[13] On 5 November 2019 Harris and Challen released the book Against All Odds chronicling their participation in the rescue of the boys from the Tham Luang Cave.