Jons Cave is the newest site on Brisbane Scuba's list of Moreton Island dives, described as a recently discovered cave system off the eastern coast of the island. It has multiple entry and exit points, with nice wide openings at at least two of them, but some passages are tight and require careful buoyancy and trim; the operator warns that it is not for divers uncomfortable with squeezes. Part of the system opens into the seafloor, where the cave passes over sedimentary rock beneath the granite, an unusual formation for this coast.

The upper level of the reef is covered in kelp gardens, typical of Moreton's eastern side, where cooler upwelling and exposure produce a mix of temperate and subtropical life. Inside the cave, crayfish shelter in the cracks and black corals grow on the walls, a sign of the low light. The surrounding reef shares the character of nearby China Wall and Cherubs Cave: granite outcrops, gutters and kelp, with turtles, wobbegongs and pelagic fish, and grey nurse sharks in the gutters in winter.

Depths are not published. Because the site is new, detailed layout information is still limited, and divers should treat the operator's briefing as essential. The minimum requirement set by Brisbane Scuba is Advanced Open Water.

For cave-curious divers who have done the Moreton classics, it offers something genuinely different, provided the sea is calm enough to dive the eastern coast. Winter trips to the eastern side also coincide with the humpback whale migration, and whales are frequently seen on the run down the coast.

Boat access only, on Brisbane Scuba day trips from Manly Boat Harbour (corner of Royal Esplanade and Davenport Drive). The boat crosses Moreton Bay, exits via the North West Channel and runs around the northern tip of Moreton Island and down the ocean side – a long run (roughly 1.5-2 hours) that is only undertaken in calm weather, typically combined with China Wall or Cherubs Cave. No public mark is published; this is not a site for private boats without local guidance.

The eastern side of Moreton Island faces the prevailing south-east trade winds and swell, so it is dived mostly in winter when westerly winds flatten the sea. Any swell over about 1-1.5 m creates surge in the cave passages, making tight sections dangerous. North-easterly sea breezes build in the afternoon.

Visibility on the eastern sites is usually 15-25 m.

Follow the guide down to the kelp garden on the upper reef, enter by one of the wide openings and move through the system slowly in single file, exiting by another wide opening. Divers uncomfortable with tight squeezes should stay outside and explore the kelp and rocks.

Cavern-style dive with daylight exits; carry a torch and a backup; avoid silting the sedimentary floor sections.

Brisbane Scuba (Manly) – occasional eastern Moreton day trips; no other regular operator found.