A cavern dive is not a cave dive: Cavern dives are conducted in the ambient light zone of the cave entrance close to open water.
Requirements for divers in the caverns are different to those for open water diving and will be clearly outlined by your cavern guide.
No knifes, Gloves or Snorkels. Touch nothing, take nothing, leave nothing. Streamline Equipment - no dangling pressure gauges and octopuses. No grabbing or pulling on speleothems. Try not to touch or disturb sediments or mark them in any way.
All open water divers must be accompanied in the caverns by a certified cavern guide, who is full cave certified and Open Water Dive Master or higher rating. The guide must use full cave equipment configuration including double tanks, which are required for air management and handling of potential emergencies. There is a maximum ratio of 4 divers allowed with each guide. Cavern divers should dive in single file behind their guide staying close together.
Air (Gas) Management
Cavern diving uses the 'rule of thirds' for gas management. One third of the initial gas supply is used for entry, one third for exit, and one third emergency reserve in case of delayed exit or to support another team member. All Cavern dives have to be no decompression dives.
Natural Daylight Zone
The area of the cavern is within the natural daylight zone of the cave entrance. Divers need to be within 60m / 200ft of the nearest open water. As well each diver must be equiped with a minimum of one light, which stays on during the entire dive.
Buoyancy and Trim
Position and buoyancy control are the key to good, safe and enjoyable cavern diving and to be honest diving in general. The divers position should be horizontal, preventing the legs and fins dropping and stirring up sediments from the floor of the cavern. As well Cavern Divers should use an appropriate propulsion technique such as the frog kick to push the water to the sides and not to the ceiling or the floor.
The lines in the caverns are laid, that there are no restrictions on the way and at all time there's space for at least two divers to dive next to each other.
Stay close to the guide line maintaining a visual reference to it at all times. Stop, skull or grim reaper signs mark the limit of the cavern zone and should not be passed. Passing these signs take you into the cave zone, which is extremly unsafe without the proper cave training and equipment.