The Great Enterprise: The History of the Spanish Armada

You will not read a better book about the great Armada of 1588, simply because this one is written by the major participants, from both sides, skilfully woven together by Stephen Usherwood with enough brief contextual explanation inserted to maintain the flow.

I'd only suggest that you do read other accounts first to familiarise yourself with the chain of events. I recommend Garrett Mattingly's “The Defeat Of The Spanish Armada”.