Thevenard Pier's pylons are decorated with corals and host shrimp, crabs, lionfish and small reef fish in 3–4 m, making it a good photography and macro site, according to the Marine Life Network. It is accessible from the island without a boat.

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 beginner. Expect to spend most of the dive around 3 m, with a maximum of about 4 m. It is a shore-access site that can be visited independently when conditions suit. Best season: April–October. Traffic: rarely dived (private boat/club only).

Onslow is about 1,380 km north of Perth, 80 km off the North West Coastal Highway. The Mackerel Islands resort on Thevenard Island is reached by the resort's ferry or charter flight from Onslow (Beadon Creek), about 22 km offshore (roughly 45 minutes by boat). There is no dedicated dive operator on the islands: divers bring their own gear and boat or hire a boat, and scuba equipment can be pre-booked through Pilbara Dive and Tours in Karratha.

Most scuba sites (3–18 m) are close to Thevenard; the house reefs and pier are accessible from the beach.

The islands sit on the shallow Pilbara shelf between Exmouth Gulf and Barrow Island. Winter south-easterly and easterly trade winds and afternoon sea breezes make the open water choppy; mornings are calmest. Tides are moderate (around 2 m) but currents run around the reefs.

Visibility typically 5–15 m. Cyclone season November–April — the Onslow coast is highly cyclone-prone. Stingers possible in the warmer months.

Enter beside the pier (check for boat movements), swim slowly along the pylons looking for shrimps, crabs and lionfish, and return the same way.

No resident dive operator – divers bring their own gear and boat (boat hire available at the resort); scuba gear hire via Pilbara Dive and Tours, Karratha, with advance notice.