Dean and the crew head to Middleton Reef for a mesmerizing ocean swim in water 4.5km deep; a tiger shark appears at the reef.

Dean and the crew explore the shipwreck Annasona, and discover an inside out reef called The Blue Hole; a sudden and nasty storm puts them in danger of becoming shipwrecked themselves.

Bad weather forces Dean and the crew back towards the Australian mainland; Dean takes his camera into the middle of a bait ball with dolphins and seals feasting on the tight school of fish.

The crew takes advantage of a sandy cay which provides brief relief from the tight quarters; the island proves to be a major rookery for Booby Birds which leave an unwanted gift on deck.

Dean sets a free dive challenge to experience the wonders of a special coral bombora; Tyler and Dean scramble to fix the broken generator.

Next stop is Marion Reef which is famous for sea snakes, and Lauren, who has a snake phobia, is not looking forward to it.