Alnwick Poison Garden
> Location: Alnwick, Northumberland, England
This enclosure of colorful flowers and ornamentals at Alnwick Castle is landscaped with solely toxic and deadly plants including henbane, castor plants, and strychnine trees. Visitors are warned not to touch or smell the plants, and some species are even kept in locked cages.
Blue Hole
> Location: Sinai, Egypt, on the coast of the Red Sea
A 300-foot sinkhole that draws scuba divers and free divers, this notorious attraction has claimed an estimated 200 lives in recent years. A narrow tunnel called the Arch leads from the hole into open waters, and is the site of most of the accidents, as divers can become disoriented in the tunnel and drown.
Réunion Island
> Location: French island in the Indian Ocean
Over 50 shark attacks have been recorded on this island southwest of Mauritius since 1988, and at least 11 people have died in attacks since 2011. The beaches are so dangerous that swimming and surfing have been banned at any location without shark nets.
Mount Huashan
> Location: Shaanxi, China
This steep, 7,000-foot mountain in Shaanxi Province features a plank walk made of narrow wooden boards that leads to a small temple at the peak. Although there is no handrail in most places, hikers can harness themselves to a cable while they climb.
