Dangerous Country can be start from natural habitat in some area of the country, or low government law that makes society became so dangerous and high criminality. Traveling to unhabitate area is more challanging than city-travel & shopping. It can be so dangerous even imigration check will give you extra warning because some destinatiion are unavailable for traveling, usually this country are at war or some sort of conflicts.
This are some country that are very dangerous for travelers. If you have plan to go there, please be carefull and prepare for the worst.
Majority Countries in Africa such as Libya, Sudan, Somalia, Mali are listed as high thread country that usually banned from the west. Those country are actually has something beautiful for culture, nature, and animal habitat. But listed as dangerous countries because terrorism are spread over the countries. Not only terrorism things but some countries in Africa has low level of hygiene and poluted environment that makes virus and bacterial can affect you when traveling over there. We can look from the WHO survey are mostly they help for africans that are affect from some virus or diseases.
Chernobyl is located in Pripyat, city of Ukraine, the incident nuclear power plant was exploded in 1986. it’s worst nuclear disaster ever listed in history of mankind. The explosion made 40.000 people more were evacuated and relocated, nuclear blast bring radiation to that area covered approximately 1 km as high danger of radiation. Not only that, water came through river also affected from radiation that can make cancer. Soil and building are contaminated. Government of Ukraine is warned to people traveling across Pripyat.
Some country in middle east, for example Iraq, Iran, Yemen, Palestine are always in conflict territory. Some passport has to be special case of permit to allow enter this country. You have to check to immigration.