Health hazards range from mild headaches to run-ins with wild animals, but the latter happen less frequently than car accidents in the parks. To be on the safe side, you might want to keep a first-aid kit in your car or luggage, and have it handy when hiking. It should include, at the least, butterfly bandages, sterile gauze pads, adhesive tape, an antibiotic ointment, pain relievers for both children and adults, alcohol pads, a pocketknife with scissors, and tweezers.

The most common health hazard is the discomfort felt as visitors adjust to the parks' high elevations. Altitude sickness is a process that can take a day or more. Symptoms include headache, fatigue, nausea, loss of appetite, muscle pain, and lightheadedness. Doctors recommend that, until acclimated, travelers should avoid heavy exertion, consume light meals, and drink lots of liquids, avoiding those with caffeine or alcohol.

Wildlife are to be treated with utmost respect in the parks, for your health's sake and theirs. Keep your distance -- at least 100 yards if possible -- from any wild animal.

Two waterborne hazards are Giardia and Campylobacter, with symptoms that wreak havoc on the human digestive system. Untreated water from the parks' lakes and streams should be boiled for at least 5 minutes before consumption, treated with iodine pills, or pumped through a fine-mesh water filter specifically designed to remove bacteria.


The following are some general safety tips for visitors to Yosemite and Sequoia & Kings Canyon:

  • Although some of the bridges that cross rivers and streams look inviting, resist the temptation to use them as diving boards -- it's not only dangerous, but also illegal.
  • Trails, especially ones over rock and granite, can be slick. Be especially careful along any rivers or creeks, such as Mist Trail in Yosemite, where wind and water can make for treacherous conditions.
  • Always carry more than enough water, especially when going into higher elevations where the body requires more hydration.
  • Under no circumstances should food be left in tents, cabins, or cars. There are storage lockers and bear-proof containers throughout the park -- use them.
  • Under no circumstances should you feed a bear -- or any wild animal, for that matter.
  • Always carry a map if you go hiking, even for short day hikes.

Another note on safety: Nothing will ruin a trip to the parks faster than sore or wet feet. Take some time planning your travel wardrobe. Bring comfortable walking shoes that are broken in, even if you plan to keep walking to a minimum. If you want to do some serious hiking, get sturdy boots that support your ankles and wick away water. Early in the season, trails may be wet or muddy; late in the fall, you can get snowed on. The more popular trails are sometimes also used by horses, which can make stream crossings a mucky mess.

Wear clothing in layers, and bring a small backpack so that you can take those layers off and on as the temperature, altitude, and your physical exertion change. Cotton is a no-no in the backcountry; synthetic fabrics are recommended because they dry much faster. Gloves or mittens are useful before the park heats up, or in the evening when it cools down again, even in summer.

The atmosphere is thin at higher altitudes, so protect your skin. Bring a strong sunblock, a hat with a brim, and sunglasses. Insect repellent, water bottles, and a first-aid kit are also recommended.

Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.