Most cruises from Cairns are pretty predictable. You sail along the Queensland coast, head out to the Great Barrier Reef, stop to go snorkeling or scuba diving, and return to the mainland before sunset. But you’re not on a normal cruise. This one is continuing beyond the northeast coast of Australia and heading into the Coral Sea.

Your destination is the Coral Sea Islands. This Australian territory covers almost one million square kilometers in the Coral Sea. The islands—including Heralds Beacon Island, Osprey Reef, and the Willis Group—weren’t charted until 1803. Guano miners arrived in the 1870s. But no one stayed because there’s no permanent freshwater source.

Today, only Willis Island is inhabited. The southernmost Coral Sea Island lies 280 miles east of Cairns. The Australian Bureau of Meteorology maintains a weather-monitoring station on the island. Four weather observers, who live on the island for six months at a time, provide early warnings for cyclones heading toward Queensland.

The 19-acre island is ringed by a white-sand beach. Planted coconut trees stand between it and the low shrub in the center of the island. Turtles and crabs greatly outnumber people. Wedge-tailed shearwaters, black noddies, and sooty terns also call the island home. Boobies, including masked and red-footed, use it as a migratory stop. While clear blue water surrounds it for as far as the eye can see.

Unlike the meteorologists who live on Willis Island, you’re only passing by. You get to see this beautiful spot, scuba dive in unexplored waters, and watch a perfect sunset as you pass through the Coral Sea Islands. There’s nothing predictable about this trip to Australia.