[3][4][5] Zaharias is one of Australia's leading high altitude climbers, his first expedition to the Himalayas was in the early 1980s and he was a driving force of the Australian Army Alpine Club for many years.

His notable ascents include:[6] On an expedition to Ganesh IV in 1981, Zaharias was with fellow climbers Maila Pemba, David Simpson and Jim Truscott who were left stranded, without equipment and "lucky to be alive" after the avalanche destroyed the camp two killing David Sloane.

[7] In 2001, on the Army Alpine Association expedition, one of the team members and two people accompanying him were killed in an avalanche while they were doing an acclimatisation trek in Nepal several hundred kilometres away from Everest.

[1][4] The Defence Newspaper said that "It was third time lucky for Major Zac Zaharias when he eventually made it to the top of the world – conquering Mount Everest – after falling agonisingly short on two earlier attempts.

When he got there, though, there was no hooting and hollering, no singing, no dancing – just relief and a deep sense of accomplishment, and a brief moment to take in the breath-taking view before focusing on a safe descent.