Lake Bonney SE is a coastal saline lake located approximately 10 kilometres south of Millicent in the Limestone Coast region of South Australia. It is the largest inland water body in the southeast of the state, stretching roughly 23 kilometres in length with a maximum width of about 4 kilometres, a volume of approximately 200 gigalitres, and an average depth of 2 metres. The lake's shoreline spans approximately 26.7 kilometres.

Access to the lake is primarily via unsealed tracks from surrounding rural roads. The shoreline borders Crown land and Canunda National Park to the north, which facilitates pedestrian and limited vehicular access, though formalized road access remains limited. There is currently no access from Canunda National Park itself. Community consultations have highlighted the need for improved and controlled vehicle entry points to prevent environmental damage from off-road vehicles.

Paddlers should be aware of significant safety hazards within the lake. Following the 1983 Ash Wednesday bushfires, large quantities of hazardous logs were deposited into the water, leading to the lake's closure for decades. Submerged logs, wire, and other obstacles remain present in parts of the lake and pose genuine risks to watercraft. Efforts to clear these hazards have been discussed but their current extent is uncertain.

The lake has a complex water quality history. Since the 1950s, discharges from a wastewater treatment plant, pulp mill, and paper manufacturing operations caused significant nutrient enrichment, eutrophication, and high turbidity, which led to the cessation of boating and fishing by the early 1980s. Approximately 90% of nutrient loads were attributed to industrial sources, with additional contributions from agricultural runoff. Water quality improvement remains an ongoing concern and is subject to separate management processes.

Human-powered craft such as kayaks and canoes are among the types of watercraft that community members and stakeholders have advocated to permit on the lake. Consultations have called for boating access to be allowed at speeds below four knots initially, with restrictions to be reviewed as hazard clearance progresses. Paddlers should verify current regulations and any applicable restrictions before launching, as the management framework for the lake has been evolving. Toilet facilities and improved infrastructure near the lake have been identified as community priorities, though the current state of amenities on the ground should be confirmed locally before visiting.