A Maritime power is a nation with a very strong navy, which often is also a great power, or at least a regional power. A Maritime power is able to easily control their coast, and exert influence upon both nearby and far countries. A nation that dominates the world navally is known as a maritime superpower.
Historic Maritime powers
Republic of Venice dominated trade on the Mediterranean Sea
British Empire was at one point both a Superpower and Maritime power.
Soviet Union Although the USSR traditionally had a strong focus on land, a period of rapid naval expansion allowed them to dominate their area.
Current Maritime powers