Marina comes from the Latin marinus, meaning "of the sea" — the feminine of the same word that gives us "marine." The name has been used since the medieval period across the Catholic world.
Marina is enormously popular across Italy, Spain, Russia, Romania, and Latin America. In the U.S. it has been continuously in the top 1000 for over a century. Today it sits in the U.S. top 500. Marina Abramović, the Serbian-American performance artist, is a notable contemporary bearer.
Marina does not currently appear in the US Social Security Administration's top 1,000 girls' names, so we don't publish a US rank or birth count for it. That says nothing about the name's standing elsewhere in the world — only that it sits outside the ranked US data we rely on.
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In Pythagorean numerology the letters of Marina reduce to 2, The Peacemaker. This is a traditional interpretive system, not a factual claim about the name.