| 4520 | Marine landing stage facilities | |
| 9232 | Marine museums | |
| 8090 | Marine navigational schools | |
| 2422 | Marine paints, manufacturing | |
| 2813 | Marine power boilers, manufacturing | |
| 0500 | Marine products harvesting, freshwater | |
| 0500 | Marine products harvesting, salt water | |
| 5150 | Marine propulsion machinery and equipment, wholesale | |
| 3220 | Marine radio communications equipment, manufacturing | |
| 6303 | Marine salvaging service | |
| 5050 | Marine service stations, retail | |
| 6309 | Marine shipping agency | |
| 5150 | Marine supplies (dunnage), wholesale | |
| 5239 | Marine supply dealers, retail | |
| 7421 | Marine surveyor (i.e., ship appraisal) services | |
| 6720 | Marine surveyors and settling agents (insurance inspectors and adjusters) | |
| 6309 | Marine surveyors, cargo | |
| 6303 | Marine vessel traffic reporting | |
| 3511 | Marine wrecking, ships for scrap | |
| 3694 | Marionettes (puppets), manufacturing | |
| 2899 | Marker boards (i.e., whiteboards), manufacturing | |
| 3699 | Markers, fibre tip, manufacturing | |
| 3699 | Markers, soft tip (e.g., felt, fabric, plastic), manufacturing | |
| 7414 | Market consulting services | |
| 5122 | Market garden vegetables, fresh, wholesale | |
| 0112 | Market gardening | |
| 0112 | Market gardening, greenhouse | |
| 6720 | Market insurance, agents and brokers | |
| 7413 | Market research services | |
| 7513 | Marketing and consumer services, government | |
| 5121 | Marketing of swine breeding stock | |
| 5139 | Marking devices, pens and pencils, wholesale | |
| 2922 | Marking machines, metalworking, manufacturing | |
| 7492 | Marking of valuables in the home | |
| 1421 | Marl bed or pit | |
| 1421 | Marl, crushed and broken stone, quarrying | |
| 1513 | Marmalade, manufacturing | |
| 5122 | Marmalade, wholesale | |
| 2029 | Marquetry, wood, manufacturing | |
| 8532 | Marriage (family) counselling services | |