How close to neutral buoyancy are they? Their web-site shows one lying underwater, so I assume they don't float. But close?
To my mind, it's a shame that they don't use a higher-capacity battery. But I can see why they don't, given the configuration they have, and the intention of being able to reverse the end-cap so that it can either shine into the tube or shine outward, flashlight style. What are the run-times on hi, low, and flash?
Any current owners want to guess the lumen output? Since we're looking at a 5mm LED driven off 2032's, I'm thinking it will be more or less like a Photon, so maybe 10-15 lumen tops? (That's for white--estimating lumen on colors is always trickier).
Although I'm not crazy about the battery, I am somewhat tempted....