Can your bring a backpack and water?

Food not allowed water bottle no problem but make it clean. I think u won't feel thirsty in side

I brought my 32oz water canteen without issue (Takeya, like ThermoFlask). Although, I went on the hour tour (beginner), I don't know how much of a backpack and water bottle will fit on the other tours.

Food is not allowed inside the cavern. Water bottle I believe they would allow as long as you bring it back. Best is to call them and check

You can, but they also have a cafe there and sell beverages

Yeah and not a bad idea to bring a flashlight too