- Bison attacks (park visitors usually get too close to take pictures with or pet huge animals who can stomp them to death).
- Poisonous gas (hydrogen sulfide gas and carbon dioxide which emanate from the geysers and are also found in caves or in trenches or dug holes)
- Ingesting poisonous plants like water hemlock, confusing it with an edible plant.
- Poisonous mushrooms (there are six types in Yellowstone National Park, i.e., the death cap, the destroying angel, the deadly conocybe, the deadly cort, the deadly galerina, and the conifer false morel).
- Falls off the rim of a gorge or inner gorge like the Grand Canyon.
- Falls while rock climbing or rappelling.
- Fatal goring by mountain goats (it is rare, but it happens)
- Attack from coyotes and wolves.
- Attacks from a pregnant elk or a momma bear with cubs.
- Attacks from mountain lions.
- Poisonous snake bites while far away from any medical help.
- Scorpion bites especially in Arizona’s Grand Canyon.
- Death from avalanches and freezing (at least six people died this way inside Yellowstone National Park).
- Freak accidents such as death by a cave-in when an embankment broke free and buried Peter Hanson in 1907 – he died of asphyxia in Yellowstone.