Diving into cool water is simply part of the holidays. You should, however, always be aware of the risks related to this. Do not dive into any bodies of water if you aren’t absolutely sure how deep they are. You should particularly avoid diving into unfamiliar waters at night, as it’s virtually impossible to accurately assess the depth of water and its current with any certainty in the dark.
Respect the local rules and regulations. These are in place to protect you against potential risks. In some places in the world, flouting local rules can cost a pretty penny, for example, the flip-flop ban in the popular tourist region of Cinque Terre, which if violated can incur a fine of up to EUR 2,500.