You want to come back from your trip with a few things that make it worth it: some rad photos, a few good stories, some laughs. Maybe not so much things like violent diarrhea, rashes, puncture wounds, black fingers and toes. But, as some folks have pointed out, true adventure begins when things start going wrong. Here are a few of those things.

1. Giardia
On that backpacking trip, you thought that “clear mountain stream” would be okay to drink from and that you probably didn’t need to treat the water. When you get home, you find out that was a bad idea, as you spend days on the toilet, evacuating gazillions of rapidly-reproducing organisms from your intestines.
Symptoms: Violent diarrhea, gas, bloating, abdominal cramps, upset stomach, nausea
Common cause: Drinking untreated water
Prevention: Boil or treat water with chemical or UV means

2. Sunburn
Sunscreen? Ha! “I burn once, then I have a nice tan the rest of the summer.” Not scientifically true. The mountains can be cold and snowy, but that doesn’t mean our friend the sun isn’t slowly cooking your exposed skin as you walk around at high altitudes. In fact, it’s bouncing off the snow in front of you and hitting places like the underside of your nose and chin. You ever see photos of Middle Eastern desert-dwelling folks walking around with their shirts off to “catch some rays”? Turns out those guys know something after hanging out in the sun for thousands of years.
Symptoms: Red, irritated skin; swelling, peeling of epidermis; pain or tenderness in skin; blistering
Common cause: Forgetting to apply or judiciously re-apply sunblock during periods of exposure to sunlight when hiking, skiing, climbing, bicycling, running
Prevention: Use of sunblock, covering exposed skin with clothing and hats, only going outdoors at night

3. Malaria
So mosquitoes are not just unpopular for pissing you off when they bite you and leave itchy bumps for days at a time. They also (in some areas of the world) carry diseases that can kill you, like malaria, which causes a million deaths a year worldwide.
Symptoms: Shaking chills, fever, profuse sweating, diarrhea, headache, vomiting
Common cause: Bite from malaria-infected mosquito in tropical or subtropical country
Prevention: Use of insect repellent, head nets and nets over bed at night; avoid travel tropical and subtropical countries

4. Altitude sickness
If the “Death Zone” is the area above 24,000 feet, maybe the area between 8,000 feet and, say 15,000 feet should be called the “Hangover Zone”: even in mountainous areas in the Lower 48, the decreased density of air makes it harder to breathe, and if you don’t watch yourself, you can end up feeling like you spent the previous evening doing kegstands and Jell-O shots.
Symptoms: Headache, nausea, loss of appetite, dizziness, insomnia, vomiting, lethargy
Common cause: Ascending too fast to altitudes 8,000 feet or higher.
Prevention: Acclimate before ascending to high altitude, stay hydrated and force yourself to eat even when you don’t feel hungry; stay on flat ground lower than 8,000 feet.

5. Jellyfish stings
Anybody not scared of jellyfish? Yes, they’re beautiful in a way, but best viewed from behind a protective layer of aquarium glass, or a wetsuit. When they touch you in the water, it’s not a kiss or a hug, it’s a sting. And it is not awesome.
Symptoms: Stinging pain, itching, rash, welts; later nausea, vomiting, diarrhea, spasms, numbness; extreme reactions include coma, difficulty breathing, death
Common cause: Swimming without a wetsuit in ocean water with high population of jellyfish
Prevention: Swim in wetsuit; stay out of ocean

6. Shark bite
It’s no secret that shark attacks are actually pretty rare, and that the media, and humans’ tendency to react to stories instead of statistics, has made us a little more paranoid about shark attacks than perhaps we should be. That’s an interesting discussion, and probably not so much at the front of your mind when you’re swimming along in the ocean a shark takes a bite out of your leg. Or, takes your leg.
Symptoms: Bleeding, severed appendages, puncture wounds, teeth marks on skin
Common cause: Encountering a shark while swimming in its habitat: the ocean
Prevention: Stay out of ocean water with high marine mammal populations; stay out of ocean completely; develop mastery of pole-spear or spear-gun; do not dress like seal

7. Mauling by bear, mountain lion
A friend of mine says he thinks your odds are better in grizzly bear territory than in water where sharks swim, because at least when you’re on land you can arguably move quite a bit faster that when you’re in the ocean. Still, you’re not at the top of the food chain, and pissing off a grizzly bear should not be at the top of your to-do list in the outdoors. Mountain lions are just as dangerous, but offer less warning — if you spend any significant amount of time hiking or running in mountain lion habitat, you’ve probably been tracked by one at least once without knowing it.
Symptoms: Pain, broken bones, severed appendages, tissue lacerations, internal injuries
Common cause: Encountering a bear or mountain lion in the wild
Prevention: Carry bear spray when hiking; avoid hiking in bear and mountain lion habitats; do not hike while wearing Lady Gaga meat suit

8. Cactus wounds
When you’re mountain biking, falling onto a rock sucks because rocks are hard. Falling into a cactus sucks worse because they can leave a million little holes in your skin, and sometimes a million little needles that you have to pull out, and sometimes barbed needles — which you might need a pliers to extract. Falling into a garden of wild roses is preferred 10 to 1 over falling into a prickly pear.
Symptoms: puncture wound, bleeding, pain
Common cause: Contact with cactus or cacti
Prevention: Avoid sitting on, brushing against, or crashing bicycles into cacti; avoid desert terrain

9. Rattlesnake bites
Lots of people hate snakes. This could be due to any number of reasons, including the fact that they don’t have legs, the first Indiana Jones movie, or because rattlesnake heads can see, and inflict venomous bites up to an hour after being severed from the body. Rattlesnakes aren’t out there hunting for humans to bite; most of the time, if you just stay away from them, they’ll stay away from you — a common cause for rattlesnake bites is “intentional interaction with snakes,” i.e., someone thought it would be cool to pick one up, which is not smart. But sometimes, you just unintentionally surprise a snake, and that’s not good either, if they get their fangs into you.
Symptoms: Puncture wounds, swelling, severe pain, tingling, anxiety; later nausea, vomiting, hemorrhaging, and heart failure.
Common cause: Not avoiding rattlesnakes
Prevention: If perchance you see a snake in the wild, do not attempt to pick it up, pet it or wrassle it. Avoid contact.

10. Tickborne illnesses
Scientists have never referred to ticks as “the ninjas of the arachnid world,” but maybe they should. You don’t see them, you don’t hear them, but you get home from a hike and you find one dug into your skin with its hind legs sticking out. Nobody likes that. Especially when they have diseases.
Symptoms: Fever, chills, aches, various rashes; long-term illnesses like Lyme disease and Rocky Mountain spotted fever
Common cause: bites from ticks
Prevention: Wearing long-sleeve shirts and long pants treated in permethrin, applying 20 percent-plus DEET sprays to skin; avoiding tick habitats (humid, forested areas)

12. Frostbite
Mountaineering history is rife with folks who have spent time at high altitudes and lost fingers and toes to frostbite, and/or the ensuing gangrene that moves in once skin cells have developed severe frostbite. Summiting is cool, and so are your fingers, and sometimes you don’t finish an expedition with both.
Symptoms: Numbness, tingling; white, hard or waxy-looking skin, usually in extremities (toes and fingers)
Common cause: Prolonged exposure to cold temperatures
Prevention: Avoidance of cold temperatures; avoidance of high-altitude mountaineering. See also: Cabo San Lucas.

13. Trench foot
Trench foot gets its name from where it was commonly discovered: on the feet of soldiers who fought in trenches in World War I. Nowadays, it happens whenever feet are kept in cold, damp places for long periods of time — long boat trips, long hikes in wet areas. It’s not appetizing, and just like frostbite, can result in gangrene, and then amputation.
Symptoms: Numbness, red or blue color due to poor circulation, decaying odor, blisters, open sores
Common cause: Prolonged exposure of feet to cold, damp, unsanitary conditions
Prevention: Keeping feet warm and dry; avoiding long cold kayak trips; stay out of trenches

14. Poison ivy rash
Poison ivy rash isn’t something everyone experiences — it’s an allergy to urushiol, a chemical found in poison ivy. But at least 50 percent of people who come into contact with poison ivy have a reaction to it, and 100 percent of those people don’t think it’s pleasant.
Symptoms: Itching, redness, swelling, blisters
Common cause: Contact with poison ivy or objects that have contacted poison ivy (shoes, pants, etc.)
Prevention: Identifying and avoiding contact with poison ivy; avoiding North America

15. Bee stings
Lots of people like honey. Lots of people are worried about the effects of colony collapse disorder. No one is excited about getting stung by bees, especially folks who have severe allergies to bees and can go into anaphylactic shock after a sting.
Symptoms: Sharp pain, redness, swelling, allergic reactions; in some cases, death
Common cause: Contact with bees
Prevention: Avoid bees, avoid bee and wasp nests; carry epinephrine

16. Death
Of all the things that can happen in the outdoors, death is the least desirable.
Symptoms: Lack of mobility, inescapable darkness, feeling of walking toward light at end of tunnel
Common cause: Fall from height, lack of oxygen due to being under water or snow, exposure to cold temperatures, excessive dehydration, trauma, poisoning
Prevention: Impossible; procrastination is possible, even desirable