Natural Wonders brainstorming

[Steb]

Two cool and unusual natural wonders I just added to The Spreadsheet:

• Catatumbo lightning, the phenomenon in Venezuela where lightning "occurs during 140 to 160 nights a year, nine hours per day, and with lightning flashes from 16 to 40 times per minute"
• Oklo natural fission reactor, in Gabon, the only place in the world where nuclear fission occurs without human intervention

I've also been wondering if some highly interesting man-made disasters should be "natural wonders." The Door to Hell in Uzbekistan is already in the list, but that could mean adding things like the Titanic wreck, or the Chernobyl Exclusion Zone. These places are "natural" in that they're unintentional, and they're certainly not regular wonders. One could argue that they fit the natural wonder idea of exploring unusual places.