Michael leaves Australia when the family’s boat sets off from there and heads into the Coral Sea toward Papua New Guinea; the key incident that separates him from the boat happens on July 28, 1988, during that leg of the journey, when he goes overboard and wakes up on the island the next morning.

In context

In Kensuke’s Kingdom , Australia is not where Michael’s adventure ends; it’s the last major stop before the storm and the accident that strand him. The story then shifts from travel to survival after that point.

Quick answer

  • Michael leaves Australia during the voyage section after the family’s stay there.
  • He is lost at sea on July 28, 1988, while the boat is sailing away from Australia toward Papua New Guinea.
  • He wakes up on the island the next morning, beginning the main island storyline.

Note

The title you wrote says “Ken’s Kingdom,” but the book is usually referred to as Kensuke’s Kingdom.