Meet the site
Black Flag is regarded by the Marine Life Network as the premier dive in the Mackerel Islands archipelago. The reef has caves, ledges and canyons at 10–17 m and excellent fish life: snapper, batfish, baitfish, silver drummer, groper, sweetlips and emperor.
About the Mackerel Islands: the group of ten low islands off Onslow, including Thevenard and Direction islands, sits just north of the Ningaloo Coast and Exmouth Gulf. The Marine Life Network documents a dozen dive sites within easy reach of Thevenard, from shallow coral heads to ledges, caves and canyons at up to 20 m, and the resort notes whales, dolphins, groper, reef sharks, stingrays, wobbegongs, turtles and thick schools of trevally, snapper, fusiliers and batfish. With no resident operator and few visiting divers, the reefs are among the least dived in the region — ideal for self-sufficient divers with their own boat.
Planning notes: Open Water certification is recommended and the site is rated intermediate. Expect to spend most of the dive around 14 m, with a maximum of about 17 m. Access is by boat only, and site selection depends on wind, swell and tide on the day. Best season: April–October. Traffic: rarely dived (private boat/club only).
Research this site before booking Stored site notes may be historical. These questions highlight gaps without turning old instructions into a current dive plan.
Black Flag is recorded as Reef in Pilbara & Dampier. The listed access is boat. Confirm the actual meeting point, route and permission to visit; a map pin does not establish any of these.
Topics flagged by the stored research
These are questions prompted by the existing notes, not a verified or complete hazard assessment.
- Current and timing
- Ask how the operator assesses the current window for the actual route. Historical tide notes are not a departure instruction.
- Planned depth
- Confirm the intended route and training requirements; the recorded maximum is not a target.
Historical access notes exist for this record, but have not been independently verified for current use. Request current directions from the operator or site manager rather than following an old entry description.
Questions, answered
Is Black Flag suitable for my certification?
The record lists Open Water. That does not establish suitability for every route or day. Share your training, recent experience and equipment needs with the operator and ask about the specific proposed dive.
Can I book Black Flag through YouDive?
YouDive is an independent research directory. Contact an operator directly to confirm whether it currently runs the trip, the inclusions and the booking terms.
What you might see
Snapper, batfish, baitfish, silver drummer, groper, sweetlips, emperor
Location
Premier reef in the Mackerel Islands group with caves, ledges and canyons at 10–17 m.
Facilities nearby
Mackerel Islands resort on Thevenard Island: accommodation, snorkel gear hire, boat hire. No air fills – bring filled cylinders or arrange via Karratha.
Before you make plans
Conditions, access and operator schedules can change. This is a location guide, not a dive plan. Ask a local operator about current conditions and suitability for your training and experience.
Sources & further reading
marinelife.org.aumackerelislands.com.auRecord updated 26 Sept 2026. Source claims are being reviewed.