From the Latin "maritimus", maritime refers to things relating to the Sea.
A maritime nation is one who borders the sea and uses it whether it be Commerce, War or to define a territorial boundary while a maritime activity are those activities using the sea to convey or produce its end result.
England is a maritime nation while Fishing is a maritime activity.
Maritime cultures have left a strong imprint on our daily lives, with phrases such as "Fish out of Water", "Out of commission", "Down the hatch", and "Learn the ropes" all having originated from maritime terminology.
Maritime law (also referred to as Admiralty law) is a distinct body of Law which governs maritime questions and offenses.