This is a really useful diving accessory. I dive a lot of caves and a few wrecks, it is fine for lighting instruments and details near you. No good as a principal light source but fine if your first torch fails. It also identifies you if you are in a big group as nobody else will have one. This is my second starlight as I stupidly left the first in a damp store with the battery still in (beaver warn not to do this). The first was below 40m occasionally and never failed.
Torches work but only for close up things, my head was on the ground before I could see it. If your expecting to see the ground I would buy something more powerful. No use for Loch Ness,, !! good for your buddy to identify you in a crowd if it’s a busy dive !!!!