map, altimeter, compass, GPS device, personal locator beacon

sunglasses, sun protective clothing, sunscreen

a first aid kit, wrapped in waterproof packaging

hikers on a short trip may also carry a multi-tool, strong adhesive tape and cordage; on a longer trip, further small tools may be useful

the means to both start and sustain a fire; either a butane lighter or matches, or other fire making device. Firestarters for igniting even wet wood, and in areas where no firewood will be available, a stove is highly advisable.

plastic tube tent, jumbo plastic trash bag or bivy sack

at least one day's food for a short hike, that should require no cooking.

drinking water and the skills and tools to purify water

additional items may be needed if spending the night in the emergency shelter