Even if the invite said clothes were optional, you should probably still keep your clothes on.
Do you care about Israel? Probably not, but it won't kill you to learn a thing or two today as you ignore your boss at work to browse Break instead.
Compress Bandages: Get the bleeding stopped and keep it from starting back again. You might be waiting a long time down there, so buy yourself some time.
Thermal Socks: Bring along a couple of pairs. Keep those feet warm and dry because it can get cold and damp down there.
Gas Mask: Poisonous gases are a major cause of death in mining disasters. This is a must to keep you breathing and also protect the eyes from dust and debris.
Fire Blanket: You can put out a fire with it, use it to protect your skin from flames, or it can keep you warm when temperatures drop to freezing.