What you are allowed to do in a 'marine national park' depends on what country and state/province the park is in as the rules - and the actual names - vary a lot from place to place.
In Australia the different types of parks or 'protected area' include: marine national parks, marine reserves, marine sanctuaries, marine conservation areas, marine management areas, marine reserves, marine reserve areas and marine parks.
Most marine protected areas have rules that limit or prohibit activities that impact on the marine animals and plants in a way that is inconsistent with the reason the protected area was set up.
For example - compare different types of marine parks in NSW, Victoria and Western Australia.
Watamu Marine National Park was created in 1968.
Dongsha Marine National Park was created in 2007.
Ainos national park alonnisos marine park oeta national park olympus national park parnassos national park parnitha national park pindus national park prespes national park samaria national park sounio nationalpark vikos-aoos national park zakynthos national marine park
Gulf of Mannar Marine National Park was created in 1986.
Point Hicks Marine National Park was created in 2003.
Karaburun-Sazan National Marine Park was created in 2010.
Kisite-Mpunguti Marine National Park was created in 1973.
Ste Anne Marine National Park was created in 1973.
Isla Bastimentos National Marine Park was created in 1988.
Cape Howe Marine National Park was created in 2003.
Rani Jhansi Marine National Park was created in 1996.
Tarutao National Marine Park was created on 1974-04-19.