O
- Oak Canyon Trail
- Oak Flat Loop
- Oak-Hill-Gardens to Waltheof Gardens
- Oak Point Nature Preserve
- Oak Point Nature Preserve
- Oaks Bottom: Bluff Trail
- Oatmeal Bowl
- Oatmeal Bowl Powder Fields
- Obergabelhorn, 4063m. ENE Ridge via Wellenkuppe.
- Oberhoresee
- Oberjoch > Großer Hirschberg > Ornach
- Oberjoch Resort Ski Tour
- Obertraun - Bad Aussee Rennradtour
- Obertrauner Themenweg "Durch Kalk und Karst"
- Observation Hill Trail
- Observation Point
- Observation Point to Geyser Hill
- Observation Subpeak (2950 m) south ridge and north glacier
- Ocean Trails Reserve
- Ocean Trails Reserve
- Ochsenboden / Flexenmulde
- Ocotillo / Sidewinder Loop
- October / Arrowhead Skin Track
- October Bowl Corner Pocket
- October Bowl East Face
- October Chute
- Octopus's Garden
- Odell's Gully
- Odyssey
- Odyssey
- Ofer Forest: Ridge Line Loop
- Offa's Dyke Path
- Off corner on way to Gron
- Off Marmotttes
- Off side of Corbalanches
- Off side of Marvel
- Off the Top
- Ofterschwang Resort Ski Tour
- Ogden Shoulder
- "O" Glade
- Ohai Trail Loop
- Ohana Trail Loop
- Ohhhh's Traverse
- Oil Well Flats
- Oil Well Flats: Island in the Sky
- Oil Well Flats: Island in the Sky
- Oil Well Flats: MOOve Over
- Ojitos -> South Boundary Loop
- Ojitos -> South Boundary Loop
- Okanagan High Rim Trail - Northern Section
- Okanagan High Rim Trail - Southern Section
- Øksehøgget Couloir
- Oksen (1241m)
- Oksetinden and Kjempetinden
- Old Butt Knob / Shining Creek Path Loop
- Old Caves Crater
- Old Chute Ski Descent
- Old Clot Gauthier Drag
- Old Cove Landing Loop
- Old Deer Park Parkrun
- Old Dominion 100
- Old Faithful Chute
- Old Ghost Road
- Old Ghost Road - IMBA Epic
- Old Glory
- Old Gordon Trail
- Old Growth / Benson & Hedges
- Old Ingraham Highway
- Old Isolée
- Old Laurel Run
- Old Man of Coniston
- Old Mans
- Old Man Storr Ski-tour
- Old Monarch Pass
- Old Nosedive
- Old Rag Loop
- Old Soldeu
- O'Leary Mountain Loop
- O'Leary Mountain Shuttle
- O'Leary Peak