Access to the water’s edge is via an artificial cutting on the southern side of the sinkhole and a metal stairway that leads to a small floating pontoon.

[10] The underwater visibility is normally poor, but can at times improve at depth and seasonal/longer-term changes in the regional water table can result in high/low variations of around 4 metres (13 ft).

It is theorised that these cenotes were formed by the collapse of large underground water-filled chambers following the lowering of sea levels at the most recent Glacial Maximum about 20,000 years ago.

The chambers themselves are likely to have been formed by groundwater acidified by gaseous Carbon Dioxide (CO2) rising up through fractures from the magma chambers during the volcanic eruptions occurring during the Pleistocene and the Holocene rather than by the usual acidification process involving the absorption of atmospheric CO2 by water prior to entering the water table.

[8] The District Council of Grant installed stairs and a floating pontoon in 2002 to improve the lake’s amenity for both residents and visitors after a review of public safety.