Carbide lamps are also nearly indestructible. That's not to say they won't go out after you drop one. But if it does, you just recover the lamp from where it lies and light it up again. But all things considered, a good carbide lamp is a reliable companion. In the mid 70's I started heading off to distant lands on expedition caving trips.
Long rope drops through water falls.
A carbide lamp takes only 6 seconds to burn through a rope with your weight on it. And like I said, I never did find a way to get a carbide lamp to work under water. Electric lights were beginning to look like a good option. The battery holders were left exposed for easy cleaning. In the grand scheme of things, it wasn't an issue.