It is a legal requirement to wear a life jacket in most states. Please check your state's current laws for the most up to date information.
WA: https://www.transport.wa.gov.au/imarine/paddle-craft.asp
SA: https://www.sa.gov.au/topics/boating-and-marine/boat-and-marine-safety/boating-safely/kayaking-and-canoeing
QLD: https://www.publications.qld.gov.au/dataset/recreational-boating-and-fishing
NSW: https://www.rms.nsw.gov.au/maritime/safety-rules/other-boating/canoes-and-kayaks.html
Vic: https://transportsafety.vic.gov.au/maritime-safety/recreational-vessel-operators/paddle-craft
Tas: https://www.mast.tas.gov.au/recreational/kayak-canoe/
NT: https://nt.gov.au/marine/marine-safety/guides-and-notices/marine-safety-guide