Why did cutting the Confederacy off from seaborne commerce prove difficult at first?

Cutting the Confederacy off from seaborne commerce proved difficult at first due to the vast coastline and numerous ports that made it challenging for the Union Navy to enforce a complete blockade. Additionally, the Confederacy developed innovative tactics, such as the use of small, fast vessels and blockade runners, to evade Union forces and continue trading with foreign nations. The Union's initial naval resources were also limited, and it took time to build a sufficient fleet to effectively patrol the extensive Southern coastline. As a result, the blockade's effectiveness evolved gradually, becoming more stringent over time.