Mountaineering, also called mountain climbing, the sport of attaining, or attempting to attain, high points in mountainous regions, mainly for the pleasure of the climb.
Navigation
map, altimeter, compass, [GPS device], [PLB, satellite communicator, or satellite phone], [extra batteries or battery pack]
Headlamp
plus extra batteries
Sunprotection
sunglasses, sun-protective clothes, and sunscreen
First aid
including foot care and insect repellent (if required)
Knife
plus repair kit
Fire
matches, lighter and tinder, or stove as appropriate
Shelter
carried at all times (can be a lightweight emergency bivy bag)
In mountaineering, make sure to bring extra clothes, food, and water.