I've got no associations with
Marin at all - isn't it a place name somewhere in the States? And I've got no Italian connections or even friends where I live, so
Marino would be eccentric.
Marinus is one of my all-time favourites. It works perfectly in English, has a good Latin pedigree and is one of the better Dutch/Afrikaans names. I like it much better than
Marina, though that's also good. I knew a
Marina once who was named after her father,
Marinus. No nicknames ever for either of them.