In reply to womblingfree:
Got two different ones, not sure of the makes, but one of them requires you to push a button to turn it on (easily forgotten), push it twice and it turns into a torch, Not great to find it in torch mode when need to charge a phone and it's nearly dead.
I'd go for the most basic one, plug in to charge it, and replug to charge your device, no buttons that make it a torch or something else that flattens it.
Not sure about waterproof ones as I tend to use a drybag for mine.