- CLAYTON SCANDINAVIA AS
- CleanAIR Systems, Inc.
- Cleemann Chair-Systems GmbH
- Clements Engineering (St Neots) Ltd
- Click Bond, Inc.
- CLIMAX GmbH
- Cloud Company Inc
- CLYDEUNION Pumps
- CM Technologies GmbH (formerly Kittiwake GmbH)
- CMI Marine
- CMR Controle Mesure Regulation
- CNAi
- CNIM
- COATES OFFSHORE
- Coldharbour Marine Ltd
- ColorLight AB
- Coltec Ind - Fairbanks Morse
- Coltraco Ltd
- COMBIMAC B.V.
- COMET GMBH
- Comnav Marine Ltd
- Compass Marine Services
- Compass Water Solutions
- COMPRESSED AIR CENTRE
- COMROD A/S
- COMSYSTEMS Solutions
- CONRAC GmbH
- Consilium AB
- Consilium Marine & Safety AB
- Consilium Marine Systems BV
- CONVOTHERM Elektrogeraete GmbH
- Cooper Roller Bearings Co Ltd
- Coops en Nieborg B.V.
- Copes-Vulcan Inc
- Cordoaria Oliveira Sa SA
- Corrosion & Water-Control Shared Services BV
- COSALT BV (Survitec Group)
- Cosalt GmbH
- Cosalt Head Office
- Coupling Corporation America
- Cramer Systemtechnik GmbH
- Cramm Yachting Systems
- Crestchic Loadbanks
- Crewsaver Marine Equipment
- Croon Elektrotechniek BV
- CSD Sealing Systems - North America, LLC
- Cummins Inc.
- CUMMINS NORWAY AS
- Current Corporation
- Cygnus Instruments Ltd
- D I DAVIT INTERNATIONAL GmbH
- Damen Anchor & Chain Factory (AKF)
- Dan Marine (Canada) Limited
- DANFOSS A/S
- Daniamant Electronics A/S (formerly Uni-Safe Electronics A/S)
- Danish Crane Building AS
- DANISH MARINE SYSTEM A/S
- DANSK RADIO AS
- Dasic Marine Ltd
- Datema Delfzijl BV
- Davey & Company London Ltd
- De Gerlien-Van Tiem BV
- DECKMA GmbH
- Deckma Hamburg GmbH
- Deif (UK) Ltd
- DEIF A/S
- Delta Fire Ltd
- Delta Rigging and Tools
- DEMP A/S
- Dennis Nakakita SA
- DENO COMPRESSORS
- DESARROLLO TECNICAS INDUSTRIALES DE GALICIA S.A.
- DESMI B.V.
- DESMI Pumping Technology A/S
- DESMI Ro-Clean A/S
- DETEGASA
- DEUTZ AG
- Diamond Sea Glaze
- Dibblee Tools Ltd
- DICKINSON MARINE
- DITECH SCANDINAVIA AS
- DLK Ventilatoren GmbH
- Dolphin Maritime Software Ltd
- Dometic Marine
- DOUBLE D MARINE EQUIPMENT BV
- Dr. E. Horn GmbH
- Dr. Shrink, Inc.
- Drahtseilwerk GmbH
- DSB Offshore Ltd
- Duncan Propellers Ltd
- Duramax Marine LLC
- Durapipe UK(Head office)
- DURASTIC Ltd.
- Dutch Thrustleader Marine Propulsion B.V.
- Dutchi Motors B.V.
- Dutton-Lainson Company
- DVC International ApS
- DYNALCO
- Dynamar B.V.
- Dynamic Marine Systems B.V.