| Ship Name | Hull No. | IMO No. | ENI No. | Year Built | Date Taken | Location |
|---|---|---|---|---|---|---|
| fv Oceana | BF840 | 2000 | 2015-06-08 | Troon | ||
| Oceanic Enterprise | 9086978 | 1995 | 1999-07-19 | River Mersey | ||
| HMS Ocelot | S17 | 1964 | 2002-06-04 | River Medway | ||
| rv Octans | 7013898 | 1969 | 1996-04-15 | Rotterdam | ||
| Odda | 8112641 | 1982 | 2005-05-12 | Haugesund | ||
| Oderstern | 9035838 | 1992 | 2001-08-18 | Manchester Ship Canal | ||
| Odin | 1964 | 2003-06-14 | River Mersey | |||
| Odin | 1975 | 1998-05-27 | Hamburg | |||
| Odin of Scapa | 9873931 | 2020 | 2024-05-15 | Scapa Flow | ||
| Odin of Scapa | 9873931 | 2020 | 2024-05-16 | Scapa Flow | ||
| Odin Viking | 9270397 | 2003 | 2015-05-17 | Montrose | ||
| Odin Viking | 9270397 | 2003 | 2015-09-20 | Aberdeen | ||
| Odysseus | 5284780 | 1962 | 1997-08-14 | Southampton | ||
| fv Odyssey | FR70 | 8644876 | 1979 | 2024-09-12 | Peterhead | |
| Odyssey II | 1993 | 1994-09-23 | Chicago | |||
| Öland | 9277400 | 2003 | 2011-06-26 | Rotterdam | ||
| Öland | 9277400 | 2003 | 2011-06-27 | Rotterdam | ||
| Öland | 9277400 | 2003 | 2012-06-22 | Rotterdam | ||
| Öland | 9277400 | 2003 | 2019-08-25 | River Tyne | ||
| Oevelgonne | 1998-05-27 | Hamburg | ||||
| Offshore Phantom | 2011 | 2019-05-27 | Aberdeen | |||
| rv Offshore Sensor | 9564059 | 2009 | 2024-05-13 | Kirkwall | ||
| Ogmore | 6620010 | 1967 | 2005-08-20 | Glasson Dock | ||
| RMAS Oilbird | Y25 | 1969 | 1988-08-10 | Plymouth | ||
| Oilfield | 1968 | 2000-06-01 | Valletta | |||
| RMAS Oilman | Y26 | 1969 | 1996-05-06 | Plymouth | ||
| Oilstone | 1968 | 2000-06-01 | Valletta | |||
| RMAS Oilwell | Y23 | 1969 | 1988-07-25 | Portsmouth Harbour | ||
| Okapi | 1972 | 1999-07-06 | Valletta | |||
| Okba Bnou Nafia | 7722360 | 1978 | 2000-06-08 | Portsmouth Harbour | ||
| Olau Hollandia | 7928811 | 1981 | 1989-06-17 | River Medway | ||
| Old London | 1979 | 2009-06-11 | River Thames | |||
| USS Oldendorf | DD972 | 1978 | 1994-09-16 | San Diego | ||
| Oleander | 7820497 | 1980 | 2002-06-22 | Dunkerque | ||
| Oleg Strashnov | 9452701 | 2010 | 2010-06-20 | Rotterdam | ||
| Oleksii Didkivskyi | 2005 | 2008-08-10 | Golf de Fos | |||
| Olga | 8843886 | 1983 | 2002-06-17 | Rotterdam | ||
| Olga | 9109548 | 1996 | 2019-07-12 | River Tyne | ||
| Olga I | 1972 | 1997-06-07 | Rendsburg | |||
| Oliphant | 2004 | 2014-07-18 | River Humber | |||
| fv Olive Branch | N19 | 1971 | 2009-07-18 | Kirkcudbright | ||
| fv Olive Branch | N19 | 1971 | 2010-04-04 | Kirkcudbright | ||
| RNLB Olive Laura Deare | E-002 | 2001 | 2006-08-10 | River Thames | ||
| Oliver B | 1988 | 2013-06-10 | River Beaulieu | |||
| Oliver Felix | 1962 | 2008-06-15 | Southampton | |||
| Olivia | 7925273 | 1982 | 2001-09-01 | River Thames | ||
| Olivia | 7925273 | 1982 | 2001-09-01 | River Thames | ||
| Olivia | 7925273 | 1982 | 2002-06-22 | Calais | ||
| Olivier | 1972 | 2011-06-26 | Rotterdam | |||
| Olivier | 1986 | 1997-04-19 | Antwerp | |||
| Olivier Gerling | 1964 | 1997-04-19 | Antwerp | |||
| Oljevern 01 | 1978 | 2008-05-04 | Stavanger | |||
| RFA Olmeda | A124 | 6501331 | 1965 | 1988-07-17 | Portsmouth Harbour | |
| RFA Olmeda | A124 | 6501331 | 1965 | 1988-10-02 | Portsmouth Harbour | |
| RFA Olmeda | A124 | 6501331 | 1965 | 1989-09-17 | Portsmouth Harbour | |
| RFA Olmeda | A124 | 6501331 | 1965 | 1991-07-29 | Portsmouth Harbour | |
| RFA Olna | A123 | 6519467 | 1966 | 1990-02-03 | Southampton | |
| RFA Olna | A123 | 6519467 | 1966 | 1994-03-04 | Portsmouth Harbour | |
| Olsauger III | 1952 | 1997-06-09 | Hamburg | |||
| RFA Olwen | A122 | 6418572 | 1965 | 1994-05-29 | Portsmouth Harbour | |
| RFA Olwen | A122 | 6418572 | 1965 | 1998-07-04 | Southampton | |
| USS Olympia | SSN717 | 1984 | 2019-04-19 | Firth of Clyde | ||
| Olympia Explorer | 9183518 | 2001 | 2001-05-29 | Hamburg | ||
| Olympic Ares | 9665712 | 2013 | 2014-05-05 | Peterhead | ||
| Olympic Challenger | 9398292 | 2008 | 2015-05-21 | Scalloway | ||
| Olympic Delta | 9745768 | 2015 | 2019-05-27 | Aberdeen | ||
| Olympic Electra | 9547415 | 2011 | 2013-09-13 | Aberdeen | ||
| Olympic Electra | 9547415 | 2011 | 2013-09-13 | Aberdeen | ||
| Olympic Electra | 9547415 | 2011 | 2013-09-15 | Aberdeen | ||
| Olympic Electra | 9547415 | 2011 | 2015-05-22 | Aberdeen | ||
| Olympic Electra | 9547415 | 2011 | 2015-05-23 | Aberdeen | ||
| Olympic Electra | 9547415 | 2011 | 2015-05-24 | Aberdeen | ||
| Olympic Hercules | 9235672 | 2002 | 2014-06-11 | Aberdeen | ||
| Olympic Hercules | 9235672 | 2002 | 2014-06-14 | Aberdeen | ||
| Olympic Orion | 9617313 | 2012 | 2012-09-15 | Aberdeen | ||
| Olympic Orion | 9617313 | 2012 | 2012-09-16 | Aberdeen | ||
| Olympic Poseidon | 9171620 | 1998 | 2014-05-04 | Aberdeen | ||
| Olympic Poseidon | 9171620 | 1998 | 2014-06-08 | Aberdeen | ||
| Olympic Poseidon | 9171620 | 1998 | 2015-09-20 | Aberdeen | ||
| Olympic Princess | 9177844 | 1999 | 2012-04-16 | Aberdeen | ||
| Olympic Princess | 9177844 | 1999 | 2014-06-11 | Aberdeen | ||
| Olympic Princess | 9177844 | 1999 | 2015-05-22 | Aberdeen | ||
| Olympic Princess | 9177844 | 1999 | 2015-05-23 | Aberdeen | ||
| Olympic Princess | 9177844 | 1999 | 2015-09-19 | Aberdeen | ||
| Olympic Triton | 9383754 | 2007 | 2012-09-14 | Aberdeen | ||
| HMS Olympus | S12 | 1962 | 1988-03-26 | Portsmouth Harbour | ||
| Olympus | 9703526 | 2014 | 2015-05-23 | Aberdeen | ||
| Olympus | 9703526 | 2014 | 2015-09-18 | Aberdeen | ||
| Omaha | 1994 | 2001-08-24 | Portsmouth Harbour | |||
| Omega | 2022-05-20 | Scalloway | ||||
| Omega I | 1974 | 1997-06-08 | Rendsburg | |||
| Omicron Titina | 9304277 | 2005 | 2019-02-09 | Firth of Forth | ||
| Omskiy-132 | 1988 | 2000-01-18 | Southampton | |||
| Omskiy-134 | 1988 | 2001-05-29 | River Elbe | |||
| Omskiy-137 | 8873087 | 1989 | 2002-06-17 | Rotterdam | ||
| Omvac Doce | 9757199 | 2015 | 2019-05-28 | Aberdeen | ||
| One Trust | 9769283 | 2017 | 2023-07-08 | Southampton | ||
| Onego Deusto | 9399129 | 2008 | 2022-05-22 | Montrose | ||
| Onego Mariner | 9631369 | 2013 | 2014-09-18 | Firth of Clyde | ||
| Onoba | 2004 | 2011-06-24 | Rotterdam |