Port Moresby in Papua New Guinea is listed as one of the world's most dangerous places and the least desirable place on earth by The Economist magazine. Theft, rape, murders and auto theft is rampant on a daily basis, and it is also recommended not to use public transportation. Beside all these concerns, the entire area is prone to seismic activities, landslides, and tsunamis.
Corryvreckan Maelstrom in Scotland is very powerful permanent whirlpool just off the coast of Scotland. Complex tidal forces and the unique geological formation combine to create an incredibly powerful, perpetually spinning whirlpool of death. A documentary team once equipped a mannequin with a life jacket and a depth gauge and then tossed it into the Corryvreckan. When it was eventually found, the depth gauge had a maximum reading of over 650 feet and it was severely damaged.
The Boiling Lake in Dominica is 200 feet wide and boils 24x7. Temperatures reach 197ºF (82-91.5ºC) on the edges. No one has ever dared to measure its temperature at the center where the water actually boils. Yes, laser thermometer is an option, but the lake is located on an island and its residents are incredibly poor. On top of that, the trek up to the boiling lake is arduous at best. Amateur hikers are told not to attempt it. The approach to the lake is steep and rocks at its edges are very slippery. The last time someone got too close, he fell in and died of his injuries.
Erta Ale in Ethiopia is a continuously erupting volcano in the middle of a desert surrounded by sulfur pits. It has very high temperatures and among native people, it’s infamous for attacking/executing outsiders, including those near Erta Ale.
Somalia is considered one of the most dangerous places in the world and not at all recommended for the tourists. It has become infamous for its piracy in the recent years. In fact, there is a pirate 'stock exchange' in Somalia where locals can invest in pirate gangs planning hijacking missions.