While OK Oliecentrale focusses on the distribution of fuels and lubricants on the mainland, the activities on water are carried out by a separate subsidiary, OK Marine, from office in Lelystad and as from 1 January 2019 from Tholen as well. OK Marine distinguishes
itself by way of their service levels and advises customers on complex issues pertaining to logistics over water, lubricating schedules, maintenance and product characteristics.

Until the end of 2017, the reselling activities were mainly on land. In the course of 2018 Catom entered the market on the water, with customers in marine contracting, the shipping industry and the cruise industry.

OK Marine owns five vessels.