Neptune Islands

The day is mostly deck time. Boats leave Port Lincoln early and cross roughly 70 km of open Southern Ocean, so the run out takes a couple of hours and is often lumpy enough to matter. Once the boat is holding in the lee, the crew set a berley trail and work a bait line off the stern, and then everyone waits. Cage rotations are short, and the crew move people in and out around whatever the sharks are doing rather than to a fixed timetable, so the day is long stretches watching the water broken by sudden turns in the cage.

There are two quite different ways to do it. The surface cage hangs off the transom with your head at the waterline and runs on hookah air piped down from the boat rather than tanks; the swell works the cage the whole time you are in it, and sharks come up the bait line from behind and pass close along the bars. The bottom cage is winched down to the seabed instead, roughly 20 m under, which puts you level with the animals against sand and reef rather than squinting down through surface glare. Not every operator runs one.

It is worth being clear that this is not conventional diving. You do not leave the cage while sharks are working the boat, there is no buoyancy to manage and no site to explore, and the water is cold enough that hoods and thick suits are standard even in the warm months. Visibility swings with wind and plankton. Cage work here is a licensed activity run by a small number of permitted operators, the island group sits inside a marine park, and nobody goes ashore, so the whole trip is boat, bars and water.

That makes it a strange fit for some divers and a good one for others. Anyone who came for reef, structure or a long relaxed bottom time will be frustrated; it works for people chasing one animal, and for photographers willing to shoot wide through bars and wait out the light. A day trip gets you there and back in one go, while multi-day charters buy more attempts at the same waiting game, which is the sensible choice if you have travelled a long way for it. Some trips also add an uncaged sea lion snorkel at a sheltered bay when conditions allow.