How many people died climbing?

I don't know if anyone has prepared an international list. For any one country you'd have to trawl through its cave-rescue reports.

Among fully-trained cave-divers, ie cavers who have learnt diving to extend their caving skills to further exploration, it's quite low.

However there have also been fatalities among open-water divers who have tried to penetrate caves such as the BlueHoles, butlacked the knowledge and skills to cope with the conditions, particularlyregarding air-supply control, navigation and loss of visibility from stirred-up silt.