Kilsby Sinkhole is located near Mount Gambier in South Australia’s Limestone Coast region. It takes its name from the Kilsby family, who have cared for  for more than 130 years. The surrounding coastline is dotted with volcanic craters, extensive cave systems, and hundreds of freshwater sinkholes.

For thousands of years, these sinkholes remained hidden underground until gradual collapses of the limestone revealed them. However, only a handful are accessible to the public. Among them, the standout is the 27-meter-deep Kilsby Sinkhole.

Kilsby Sinkhole is renowned for its exceptional underwater visibility, reaching up to 80 meters. Beams of blue light slice through the dark water, creating a unforgotten scene  Looking upward, you can see a sharp circle of sky, while below lies the rugged terrain of the sinkhole floor.

• Visibility: Crystal-clear freshwater often exceeding 50–80 m under good conditions

• Depth Range: Around 27 m for recreational freediving and deeper sections beyond under trained supervision

• Water Temperature: Approximately 16 °C year-round

• Water Conditions: Calm freshwater with no ocean swell or currents; clarity can vary with seasonal water levels

• Seasonality: Accessible year-round with consistent temperature; operations depend on booking and operator schedules

• Transportation: Road access from Mount Gambier via personal vehicle or regional transport

• Local rules: Access by prior booking only; guided dives must be arranged through licensed operators with adherence to safety and property guidelines