Many a Murdoch alumnus enjoyed veterinary opportunities with placements and employment in this practice over the subsequent years. 

In his spare time Dr Challen became a cave diver and explorer. In 2011 he made a record-setting 194 metres deep dive while caving in New Zealand. In 2020, he made a second record-setting return visit to the Pearse Resurgence in New Zealand and extended the Australasian depth record to 245m with his long-standing dive partner, Adelaide anaesthetist Richard Harris. His adventures continue with a recent 284m dive in South Africa.

In 2018, Dr Challen and Dr Harris were called upon to spearhead the effort of an international group of cave divers to rescue 12 children and their football coach from 2.2km inside the flooded Tham Luang cave in northern Thailand. 

Using previously untested techniques, over three days the boys were anaesthetised and extracted from the cave via a three hour dive. Despite there being initially little hope of success, all 13 people survived the rescue after 17 days trapped underground.

The successful rescue of all the boys and the coach became a global news story and Craig was awarded the Star of Courage for his unwavering and selfless bravery following the successful rescue of the team. In 2018s, the King of Thailand appointed Challen as a Knight Grand Cross (First Class) of the Most Admirable Order of the Direkgunabhorn. The same year Murdoch University awarded Dr Challen an Honorary Doctorate and in 2019, Dr Challen and Dr Harris were named joint Australians of the Year.