Greg's Grotto

Meet the site

Greg's Grotto is a maze of ledges and caves covered in colourful corals, sponges and gorgonians at about 14 m, with abundant reef sharks and mackerel, per the Marine Life Network.

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 14 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).

What you might see

Reef sharks, mackerel, gorgonians, sponges, corals

Location

Maze of ledges and caves covered in corals, sponges and gorgonians at about 14 m in the Mackerel Islands.

Facilities nearby

Mackerel Islands resort on Thevenard Island: accommodation, snorkel gear hire, boat hire. No air fills – bring filled cylinders or arrange via Karratha.