The Dutch rebels still possessed Ostend, so the Spanish Armada could not stop at any ports in the Netherlands, but had to rendezvous with the Duke of Parma's army at sea after it had embarked on a series of smaller ships. This made communications very difficult
The key turning point seems to have been the Battle of Gravelines, where the English used fireships. Many Spanish captains panicked, cut their anchors and allowed their ships to drift into the North Sea