Geocaching is great because of its unregulated nature. Less is more. The lack of controls and rules in this venture gives all of us the freedom to enjoy, explore, and express. As soon as anyone decides that a cache is too dangerous and shouldn't be listed, the precedent is set and the decline of geocaching imminent.
Rainbow Hydrothermal Vents is named in The Complete Idiots Guide to Geocaching as the most extreme cache. It is at bone crushing depths in the ocean. There are no warnings listed on the web page. I don't believe any are needed. It speaks for itself. I've investigated this just a bit. It is expensive, but there are submarine tours to this area. Certainly danger exsists for this cache. But danger exsists at the local park too, albeit a different kind of danger.
Deciding that a cache should not be listed, because of the risk it involves to an individual (different for each face on this Earth), is tantamount to censorship.
Where's the line to be drawn? Right here---> All caches should be reviewed for "inaccuracies, bad coordinates, and appropriateness". Because..."as the cache owner, you are responsible for the placement and care of your cache". Thats it. Nothing more.
What does that mean? What am I saying? I'm saying all caches should be listed. For who am I to decide what is safe for you? Or you? Or you? And who are you to decide what is safe for me? BTW it costs $25,000 (US) to visit the vents(travel not included).