It is a concern that citizens already are touring the...

It is a concern that citizens already are touring the Titanic and some Atlantic vent sites with deep-diving submersibles. When Yellowstone Park -- which features geothermal geysers analogous to deep-sea vents -- was established in the mid-1800s, no ordinary person could get there because it was a four-day trip by horse from the nearest rail line, but roughly 3,000,000 visited Yellowstone last year.