I have a couple glotoobs... they're OK. I have a red and green; green is definetely brighter. I believe there's also amber and white.

Available with 2 different battery types, with the CR123 being slightly higher price.

Probably would be good, but I don't know if they float. I suppose I could try it and report back later tomorrow. However, the run time isn't all that phenomenal. I put one on the dog collar for night walks, and it probably lasted ... 10-15 hours, maybe. In other words, if you're out of the boat more than 1 night, you might want something else, or at least several of them. Not sure how effective a battery change would be at sea.

Cellphones might work, but the second you get them wet they're pretty useless.