Why did the union find it difficult to maintain the blockade it set up to control southern ports?

The Union/Northern naval assets were not sufficient to blockade the littoral in it's entirety due to the lack of intimate knowledge of riverine access points and there were many blockade-runners whose ships were faster than heavy cannon-laden warships plus this was a lucrative enterprise for black-marketeers , et. al.


Good luck !


:0)Why did the union find it difficult to maintain the blockade it set up to control southern ports?
Not a big enough Navy. It is a long coast line, and the gulf is a big body of water to cover to keep ships out of New Orleans, Mississippi and Texas.