and I do not want multiple levels
I'm looking for a low-output light with the longest possible runtime. 10 lumens is fine, and I do not want multiple levels. just one long-running light. Oh and it must be 100% waterproof.
The single mode E2L has reasonable ouput (probably more than you want) regulated for 10 hours.
Not waterproof but 100 hours from a 1xAA CMG Infinity. Not sure of the lumens but comparing it to my Fenix that runs at 10 on low, I'd say the Infinity is 4 or 5 lumens.