- Ocean Imaging, Corp.4
- Ocean Tipping Points Project43
- Ochungo, P.2
- Office of Emergency Services1
- Oficional Nacional de Hidrografia y Geodesia (ONHG)16
- Okada, Gyokuzan, -18081
- Okamoto/Liskamm1
- Oklahoma State University. Department of Geography. Cartography Service133
- Olmsted, Frederick Law, 1822-19031
- Ooka, Shoken1
- Ottoman Army1
- Owen, W. F. W., 1774-18571
- Pacific Coastal and Marine Science Center183
- Pacific Fishery Management Council (U.S.)1
- Pacific Institute1
- Papua New Guinea. National Mapping Bureau8
- Parent, Jason835
- Paskevich, Valerie1
- Patterson, Tom160
- Patterson, Will63
