Spain did not explore:
O Canada
O Central America
O South America
Caribbean Islands​

O Canada

Explanation:

Have you heard of anywhere in Canada where they speak Spanish? No, I didn't think so. That's because while they were so focused on the Caribbean and Central and South America, the French got Canada, and some of the English after that little war. Also, the Spanish reached everywhere else so by process of elimination, Canada is the only one left

Hope this helps:)