Cardabia Passage is a named gap in the Ningaloo Reef north of Coral Bay, on the coast of Cardabia Station (which surrounds the town).

Passages through the reef — the 'cuts' that Coral Bay's advanced divers favour — funnel ocean water in and out of the lagoon, carrying plankton that attracts manta rays, reef sharks and schools of pelagic fish. Their walls typically carry hard and soft coral, and currents can be strong on spring tides. Expect a current-driven dive best done as a drift with a live boat and experienced guide.

About Coral Bay: the town is a small resort settlement on Bill's Bay at the southern end of the Ningaloo Coast, about 150 km south of Exmouth. The outer reef lies close to shore, so both lagoon snorkels and outer-reef dives are short boat rides away, and Coral Bay is home to Western Australia's largest resident population of reef manta rays, seen year-round. Much of the water around town lies within the Maud Sanctuary Zone, where fishing and collecting are prohibited. Advanced divers favour the 'cuts', where open-ocean water funnels through gaps in the reef and brings in sharks, mantas and pelagics, while the calm lagoon suits training and beginners. The 2025 marine heatwave affected northern and central Ningaloo most; southern areas including Coral Bay sustained less damage, according to AIMS.

Coral Bay is 150 km south of Exmouth (about 1 hr 45 min) and 1,145 km north of Perth via the North West Coastal Highway and Minilya–Exmouth Road; Learmonth airport (Exmouth) is the nearest airport. Dive and snorkel tours meet in town (Ningaloo Reef Dive meets at 8:00 am) and transfer by minibus to the Coral Bay boat ramp, about 2 km south of town via Banksia Avenue, or load from the beach. Most dive sites are within a few kilometres — 10–30 minutes by boat — either inside the lagoon, at the passages ('cuts') through the reef, or on the outer reef north of town towards Point Maud and Bateman Bay.

Coral Bay's lagoon is protected by the outer reef and faces north-west, so it stays calm in the prevailing south to south-westerly winds that close exposed coasts; the outer-reef and passage sites, however, need low swell and light winds. The afternoon south-westerly sea breeze (often 15–25 knots in spring and summer) chops up the outer sites, so dives run in the morning. Tidal flow through the passages can be strong on springs.

Visibility is usually 10–20 m, lower after the March coral spawn (in March 2022 a spawn-related low-oxygen event killed fish and coral in Bill's Bay). Cyclone season November–April; stingers possible in warm months.

Enter on the slack or early flood at the mouth of the passage, follow the reef walls of the channel with the current, and ascend with a DSMB for live-boat pickup.

DSMB and live boat.

Ningaloo Reef Dive & Snorkel – two dives daily on the 'Bay Escape' (up to 16 divers), plus full- and half-day Adventure and Manta Ray tours combining divers and snorkellers; Coral Bay Eco Tours and Ningaloo Marine Interactions/Coral Bay Eco Safaris – snorkel, manta and whale shark tours.