False Entrance takes its name from a U-shaped gully that looks like a passage into Osprey's lagoon but is blind. Spirit of Freedom calls it architecturally spectacular: bommies rise from a gully that falls to about 30 m, and blue-water swim-throughs pass between them before the reef edge drops into the abyss. Mike Ball includes it on every Osprey and Coral Sea itinerary.

The topography is the first attraction. The bommies are decorated with gorgonian fans, sea whips and soft corals, and the swim-throughs frame the open ocean beyond. Dive the World lists a wall to more than 30 m, multiple bommies and swim-throughs, with conditions that range from slack water to a strong drift.

The second attraction is the fish. Marinelife.org.au and Mike Ball both describe resident schools of big-eye trevally and barracuda, and Mike Ball advises watching for hammerheads in the cooler months. Underwater Atlas calls it the site with the reef's most intense shark action, with grey reef sharks aggregating in groups of 20–30. Manta rays, eagle rays, whitetips and triggerfish are regular, and the bommies hold scorpionfish, stonefish, banded pipefish and hawkfish.

False Entrance suits intermediate divers who are comfortable in variable current and on a wall. It rewards both wide-angle photographers, who have the swim-throughs and schools to work with, and those who simply want to hang off the edge watching sharks. When the current runs, it becomes an exciting drift; on slack water it is a place to explore the bommies at leisure. Many divers rate it alongside North Horn as the best dive of an Osprey trip.

Liveaboard only. Mike Ball's Spoilsport runs 4-night fly-dive trips (depart Cairns Thursday evening, cruise north overnight via the Ribbon Reefs, cross to Osprey, fly back from Lizard Island) and 5–7 night Coral Sea expeditions; Spirit of Freedom visits Osprey on its 4- and 7-night itineraries, with a Cairns–Lizard Island flight connection. The open-ocean crossing from the Ribbon Reefs to Osprey (about 100 km) is made overnight.

Allow 2–3 days at Osprey on a typical trip. False Entrance is on all Mike Ball Osprey itineraries and Spirit of Freedom trips; it is dived from a mooring or as a drift depending on the current.

Osprey is an isolated oceanic atoll about 350 km north-east of Cairns and roughly 100 km beyond the edge of the Great Barrier Reef, so every trip involves an overnight open-ocean crossing. Strong south-east trades (over about 25 knots, common June to August) make the crossing rough and can close the exposed eastern and southern walls; liveaboards then work the sheltered western wall and North Horn. Sep–Dec usually brings the lightest winds and visibility of 40 m or more.

Currents on the walls vary with tide and oceanic flow and can run strongly around the horns. Dec–Apr is cyclone season and trips can be cancelled or diverted to the Ribbon Reefs. False Entrance can be dived at slack water or as a strong drift; crews choose the plan on the day.

Descend into the U-shaped gully to 20–25 m, weave between the bommies and through the blue-water swim-throughs, then move onto the wall edge to watch for sharks and hammerheads. Return up the gully to the reef top for the safety stop.

Mike Ball Dive Expeditions (Spoilsport) – 4-night Osprey fly-dive, 5-night Coral Sea & Cod Hole and 7-night Coral Sea expeditions from Cairns, several a month; Spirit of Freedom – 4- and 7-night trips including Osprey, weekly.