The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.

• (DT)Ecology‏‎ (14 members)
• (DT)Energy‏‎ (10 members)
• (DT)Governance‏‎ (2 members)
• (DT)Management‏‎ (2 members)
• (DT)Shipping‏‎ (6 members)
• (NS)Currents‏‎ (1 member)
• (NS)Ecology‏‎ (28 members)
• (NS)Energy‏‎ (14 members)
• (NS)Governance‏‎ (11 members)
• (NS)Shipping‏‎ (11 members)
• Aquaculture‏‎ (5 members)
• Biodiversity indicator‏‎ (2 members)
• Birds and mammals‏‎ (5 members)
• Cables and pipelines‏‎ (10 members)
• Energy‏‎ (14 members)
• Environmental conditions‏‎ (12 members)
• ExampleCategory‏‎ (2 members)
• ExcludeFromList‏‎ (4 members)
• External link templates‏‎ (1 member)
• Fish‏‎ (10 members)
• Fishing‏‎ (14 members)
• Food infobox templates‏‎ (1 member)
• Governance‏‎ (11 members)
• Hatnote modules‏‎ (1 member)
• Infobox templates‏‎ (1 member)
• Internal category-link templates‏‎ (3 members)
• Intricate templates‏‎ (1 member)
• Lua-based templates‏‎ (4 members)
• Lua metamodules‏‎ (3 members)
• Macrobenthos‏‎ (1 member)
• Microformat (uF) message templates‏‎ (2 members)
• Military ship infobox templates‏‎ (1 member)
• Modules for image handling‏‎ (1 member)
• Modules subject to page protection‏‎ (11 members)
• Modules that add a tracking category‏‎ (6 members)
• Modules using data from Wikidata‏‎ (1 member)
• Natural resources‏‎ (2 members)
• Pages using DynamicPageList‏‎ (2 members)
• Pages using duplicate arguments in template calls‏‎ (3 members)
• Pages with broken file links‏‎ (1,143 members)
• Pages with ignored display titles‏‎ (1 member)
• Pages with non-numeric formatnum arguments‏‎ (1 member)
• Pages with script errors‏‎ (26 members)
• Pressure‏‎ (4 members)
• Protected areas‏‎ (17 members)
• Recreational‏‎ (17 members)
• Ship templates‏‎ (1 member)
• Shipping‏‎ (26 members)
• TemplateData documentation‏‎ (2 members)
• Template documentation pages‏‎ (4 members)