Luggage and bags:
NO BAGS! OF ANY KIND! PERIOD! Simple. Also, no tools to take rock samples. (Yes, a woman did try that). This rule is for security and well as for common sense. It's a cave. There are tight places. If you want, you can buy or make a holder to carry a water bottle (clear plastic). Hang it from a belt / belt loop. Two bottles of water in your coat pockets gets heavy after a while.
Clothing/Shoes/Weather Gear: Flip-flops have no place on a cave tour. Sneakers are fine on most tours. Read the tour descriptions and guides. It stays 54 degrees (F) all the time. I wore a light gortex jacket. Some people wore t-shirts and were just fine. If you get warm from the exercise, you can take a jacket off. If you get cold and don't have one, you have a problem.
Toiletries and Medical Supplies: Some tours offer no chance to use a toilet or get a drink of water. Think ahead. Parents with children take note!
Photo Equipment: Flash photos are not allowed on some tours. Really depends on the Ranger leading the tour. I do know that having a flash go off in your face after your eyes have become used to the low light hurts like hell. Some Rangers don't like for people to stop and take photos because it really slows the tour down and makes the Ranger bringing up the rear have to rush people along. My wife tried a few shots. Almost impossible without a tripod to get good ones. Some people were trying video cams with no light. don't know how that turned out.
Sturdy shoes with flat soles and lots of tread. Some cave tours require specific footwear, so be sure to inquire before you go!
Toiletries and Medical Supplies: Prepare for your tour! If you are going on a 6 hour tour, bring anything you may need. Purses, backpacks, and hip sacks are not allowed.
Photo Equipment: Even with a flash, light dissipates in the cave and it is difficult to get a photo of anything farther than 10 feet. If you are using a 35mm camera, I suggest a high speed film!!
Camping/Beach/Outdoor Gear: Apart from lantern tours, flashlights are allowed on tours. The trails in the cave are lit, but VERY dimly. If you need more light, bring your own! No matches and lighters allowed!