Music for the First Article
A Death World is a highly dangerous place, where simply going there is considered taking your life into your own hands. It could be from hazardous environmental conditions, such as an acidic swamp or poisonous fog, or from powerful native predators (Here there be Dragons, or worse, something that eats them), dangerous flora, or even all of the above. It's like the entire place is deliberately hostile to human life.
Ants that spurt quick-hardening glue that can trap you or close off your airways. Plants that shoot spores that, if they touch you, starts growing in your skin and spreads fast. Tons and tons of carnivorous beasts. Hostile, invisible natives. Honestly, when the army of insane alien killing machines is the least of your worries, things are bad.
Sometimes they're Glass beaches lapped by acid seas. Jungles full of hostile plants and deadly mechanical traps. Frozen wastelands patrolled by packs of man-eating wolves.
They're are actually many examples in real life
Outer space. There is nothing organic that can survive for long in the vacuum. Unshielded, vast amounts of radiation will kill any human, and if that doesn't do the trick, will leave unpleasant mutations and other fun surprises in the body - and that's if the temperature doesn't do you in. Depending on how close to a star you are, wherever the sun hits can be hot enough to just flashboil your flesh off - and the shade isn't any better, as it'll be well below freezing. Meteorites and other flying objects, often moving at speeds that make fighter jets look like snails, can ram into flesh. The lack of pressure will cause organs to swell and burst. And if asphyxiation doesn't do you in, the lack of gravity will warp bones and muscles into being useless after a while.
Venus is certainly the best example of the trope in our solar system. The atmosphere is almost entirely carbon dioxide, the sky is constantly overcast with clouds of sulfuric acid, and the global climate is in excess of 500 degrees Celsius. All probes sent to Venus were quickly destroyed by the heat, or crushed by the air pressure, which is about ninety times that of Earth's at sea level.
Africa. It's the only place where a menagerie of large mammals still remain, the heat is very intense, there's an outbreak of all kinds of diseases, and it's home to the most dangerous snakes on Earth.
New Mexico has a stretch of desert called "the Jornada Del Muerto," i.e., The Dead Man's Trail. This is a chillingly lifeless hundred-mile desert trail completely devoid of life and water. Before the rise of the automobile crossing the Jornada was frequently deadly; when conquistadors from New Spain discovered it they named the first pueblo they found on the other side "Socorro" - Spanish for "help." In 1945 its lifelessness was confirmed when it was used as the test site for the world's first atomic bomb.
Russia. Certain regions of it are suprisingly mild as Death Worlds go, and Russians themselves find these spots rather nice to live in. However, most of it (the taiga, the tundra, the swamps) is a bona fide Death World featuring deadly frosts (Oimyakon, the Northern Hemisphere's coldest place, is here), literally man-eating swarms of vampiric gnats and huge bears (the Siberian brown ones are the size of American grizzlies, Kamchatkan ones are the size of kodiaks, and we don't even get started on polar bears) that do not fear man at all. And swamps, lots of them. Food comes from hunting and fishing, because this is permafrost country and no agriculture is possible. If that wasn't enough fun, the blistering summers are still there. It's called severely continental climate, and it's all about extremes. It's either hot or cold.
For any humans it's likely the Mesozoic era. Obviously there would be dinosaurs everywhere but there are also many more dangerous wildlife like terrestrial crocodiles, giant pterosaurs, large venomous lizards, fresh and saltwater aggressive fish, toothy birds and large dinosaur-eating amphibians to name a few potential threats found during the age of reptiles.
Antarctica. At least Australia has a permanent human population. And the interior of Antarctica doesn't permanently support any life. Emperor penguins live there part of the year to breed and raise their chicks, and the males (who stay there the longest) lose half their body weight doing it.
The Amazon Rainforest was here; you're all small-time. Everything from the plants to the bugs to the water is actively trying to kill you.
The highlands of Papua New Guinea. It's not TOO bad if you know what you're doing (like the locals) or have their help. However, the Japanese tried going through it to capture Port Moresby after their invasion fleet turned back after the Battle of the Coral Sea. An estimated 75% of their forward fighting troops were killed, wounded, or became ill, and over 60% of the total force didn't make it back to their starting point.
Ilha da Queimada Grande, a small island off the coast of Brazil, and crawling with very deadly Golden Lancehead vipers—as many as 1-per-square-meter if averaged out.
..................................But the best real life example is AustraliaMusic for the Second Half of the Article
About the only things that aren't dangerous or poisonous are some of the sheep (which aren't native to Australia). And maybe wallabies. The following things will kill you: common spiders, the most common snakes, ticks, crocodiles, sharks, jellyfish, stonefish, we have a seashell that will go for you and deliver a very painful, fast death. Even (male) platypus are poisonous.
Platypodes aren't merely venomous, they have probably the most terrifying venom in nature. The other animals on this list will just kill you, the Platypus isn't that humane. Its venom attacks the victim's pain receptors, cranking them Up to Eleven and ripping off the knob. It causes pain so horrible that even the highest non-lethal dose of morphine isn't enough. To stop the pain, doctors actually have to physically sever the nerve from the affected area to the brain because that's the only thing powerful enough.
Except that, if a spider spins a web (as in a traditional, picturebook cobweb), it won't kill you normally, just make you wish it had.
A wallaby could still probably break a few of your ribs by kicking you, and that's pretty bad as broken ribs can lead to punctured lungs or a punctured heart.
Then there's the most humiliating thing of all - mauled by Wombat.
We all know kangaroos hop around on their hind legs — well, those hind legs are strong enough to disembowel a person with a single kick. Breaking the old stereotype that island faunas are wimpy, kangaroos have proven themselves quite able to compete with other animals on the mainland.
The Australian fierce snake (named for its home, the Fierce Desert, not for its temperament, which is actually non aggressive) is considered the most poisonous snake in the world. In fact, the top nine poisonous snakes in the world are all from Australia.
Eucalyptus trees have a rather amusing tendency to explode, given the proper stressors.
Eucalypts also produce dry, waxy leaves and loose bark that fuel the frequent and highly dangerous bushfires, and have a tendency to lose branches in high winds, or just after said fires. Add in the fact that eucalypt branches are often 1-2 metres in length, and all grow from the top foot or so of trunk, and you can see that even the trees are trying to kill you.
Also, falling gum tree limbs (known as widowmakers) have caused serious property damage and deaths. And they fall with no warning. Feel like taking a nap under a gum tree during a hot day? It might be the last thing you do...
And that's just the stuff on land, they also have - apart from the sharks and saltwater crocodiles - blue ringed octopus, box jellyfish, cone snails, stingrays, etc. You know your country is scary when even the snails can kill. The aptly named Triton (not the car) is one of the few predators that will kill and eat "crown of thorns" starfish.
Emus are basically really big Velociraptor with a beak. Be glad that you do not meet their dietary needs. Cassowaries, too — which are like emus but actively aggressive towards humans. They were actually used as the models for the Velociraptor in Jurassic Park. Adding to the horror - a Cassowary is basically an emu with warpaint and an axe attached to its head.
Koalas. If you try to hug a wild one, they will be happy to "hug" you back with razor sharp claws that are designed to be habitats, they are also natural experts of biological warfare. Have you ever heard one growl at you? The cute little marsupials sound like giant ogres!
Out of all these critters, the only ones that really cramp your style are the jellyfish. Sharks? There's like three left. Spiders? Don't go picking up random bits of rusty iron. Snakes? Make a lot of noise whilst walking through undergrowth, wear tough shoes, etc. Stonefish/cone shells? Don't walk barefoot on reefs. But jellyfish? "Oh, I'm sorry if you wanted to go for a swim at that otherwise harmless sandy beach when it's 42 degrees. We'll just be floating around by our thousands, invisible and potentially fatal."
Not to mention the Irukandji. The worst of the box jellyfish (an infamous class of jellyfish), they will actively seek out prey rather than drift along in the current, are the size of a fingernail, are transparent, can swim through anti-jellyfish safety nets on beaches and pack a horrifically painful sting
To elucidate a little further, it's not just the animals that can kill you, but nearly all ground everywhere that can kill you. Apart from some of the most perilous mountain ranges anywhere (with sharp drops, deceptive rock formations, crumbling earth, nexus of underground caves which you won't find your way out of without a very experienced guide, and narrow winding paths that you only can travel with immense preparation (and these are mountain ranges with absolutely tiny mountains compared to the rest of the world, just look up the Flinder's Ranges)), you have wide vast expanses of ridiculously dry desert in Western Australia that you will die in if you don't have someone who knows how to find the water hidden deep beneath the ground, a coastline with so many abrupt cliffs that if you're not careful you can drive right off, and marsh land and estuaries in Queensland that will either suck you into their swampy extremes, or leave you wandering lost for days in sand dunes. Even the bushes will try to poison you and paralyse you!
In fact everyone growing up in Darwin knows not to dig during the wet season if you have any cuts or injuries. The bacteria, Melioidosis, more commonly known as Nightcliff Gardener's Disease lives deep in the soil, but comes to the surface when it rains. It's has a nearly 90% mortality rate when untreated and there's no known vaccine.
The plants can also kill you. The Stinging Tree is aptly named; all shrubs and trees of this genus have very fine hairs which will end up in your body if you walk too close (also, said hairs SHED, so too close is probably within a 5km radius). These stingers are poisonous, and they have been known to kill horses, dogs and, yes, people. With great efficiency. Even if it doesn't kill you, the hairs - and subsequently the pain, because its the Stinging Tree for a reason, tends to last several years; the hairs are too fine to remove, and they don't break down in your body.
Australia is not just an active killer, it's also passive-aggressive. There's been no crustal overturn in most of the continent since around the time of the first dinosaurs, so the soils tend overwhelmingly to be thin and nutrient-poor, and in many places — especially in the southwest — tens of millions of years of accumulated salt spray make the ground inhospitable to vegetation not evolved to cope with it. Europeans moved to this place and set about establishing European-style agriculture. Australia blinked and chuckled grimly at that, though it's true those rabbit things are annoying.
If you think that's bad, back in the Pleistocene, when humans first arrived was even more dangerous. Carnivorous buzz-saw toothed kangaroos? Check. Monitor-lizards the size of a city bus? Check. Climbing warm-blooded saw-toothed crocodiles? Check. Gigantic killer pseudo-python? Check. Marsupial lion with sickle thumbs? Check. The Demon Duck of Doom! (I'm not joking, scientists actually call it that). Oh yeah, it's there. Ninjemys, a gigantic horned turtle built like a panzer tank (and yes, the name means exactly what you think it means and it was named after that), check.