Just thought I'd see what people use in their cave expeditions.. Do you use a hand torch or head lamp? and What strength in lumen (brightness) is necessary? Will happily accept recommendations for brand or models of lighting too. Thanks in advance

What is the safest way to ensure that a cave doesn't have a flammable/combustible gas, like methane or natural gas? Is methane the only dangerous natural gas to watch for too? (I realize its the oxygen content that matters to breath, just don't want to go boom) Since I know its odorless, and...