Pannikin Plains is the Nullarbor cave most associated with danger and drama. In 1988 an expedition led by Andrew Wight was underground when an extreme storm sent rainwater flooding into the cave, collapsing part of the dry entrance section and trapping 15 members for several days until the rubble was cleared. The episode was filmed in the documentary 'Nullarbor Dreaming' and later inspired the Hollywood film 'Sanctum', which Wight co-wrote and produced with James Cameron.

Shearwater's account of the 2023 Pannikin Plains Push Project describes the entrance 90 m above water level on the high plains, and a main tunnel with the ceiling at around 20 m and the floor closer to 40 m, running nearly a kilometre to Concord Landing, a massive dry chamber. A 2016 discovery led to exploration of Sump Three via Chapel Hill, and the 2023 team added new passage without finding the hoped-for mega-tunnel; further exploration was planned for 2025.

The cave (reference 6N49) is administered by DBCA, with applications to the District Manager at Esperance. This is exploration-grade technical cave diving – deep, remote, logistically heavy and subject to entrance instability – and is not a site for casual visits. The cave's history has made it a touchstone for Australian cave divers, and its incident informs modern expedition planning, which now routinely considers weather forecasts and entrance stability. Expeditions here are measured in weeks, not days.

The Nullarbor caves lie along the Eyre Highway between Norseman and the SA border, roughly 11-14 hours' drive from Perth. Cocklebiddy Roadhouse (fuel, meals, water, showers) is the base for the central caves; Norseman, 435 km west, is the nearest regional centre. Access to the cave entrances is by unsealed station/bush tracks (4WD recommended), and all cylinders, compressors, gas, water and rope/hauling gear must be carried in.

Pannikin Plains is close to Cocklebiddy Roadhouse (fuel, meals, water, showers). The entrance is on the high plain, 90 m above water level, requiring a long descent with equipment. Access is by DBCA permission (District Manager, Esperance).

Surface weather matters mainly for access and safety: summer temperatures can exceed 45°C, making gear hauls dangerous, while winter nights are cold. Heavy rain is rare but can flood entrances and destabilise rockpiles (the 1988 Pannikin Plains collapse followed a severe storm). Underwater conditions are stable year-round: groundwater at about 19°C (24°C at Tommy Grahams), often brackish to saline with haloclines, and visibility commonly 20-50 m or more unless disturbed.

Autumn to spring (April-October) is the usual expedition season. Pannikin Plains' entrance is vulnerable to storm runoff: in 1988 a storm flooded the cave and collapsed part of the dry section, trapping the expedition.

Exploration diving: the main tunnel runs with a ceiling around 20 m and floor near 40 m for nearly a kilometre to Concord Landing, beyond which further sumps (Sump Three via Chapel Hill) continue. Requires trimix/CCR and full expedition support.

Exploration site: trimix/CCR, stage and decompression planning, surface support and satellite communications essential. DBCA Esperance permit required; CDAA Advanced Cave-level experience.

No operator – exploration teams with DBCA permission only.