This is factually incorrect. Blockade is not a synonym of embargo. Blockade is generally an act of war, and embargo is not. Dealing with Cuba is certainly a huge PITA for the majority of trading actors because of potential blacklisting in the US, but waters around Cuba are as open as they can be, and you can check marine traffic to make sure that ships arrive to Cuban ports. Even from the US itself (cause there are exceptions from embargo such as food, and medicines).
Our Blessed Homeland :: Their Barbarous Wastes
Our Glorious Leader :: Their Wicked Despot
Our Great Religion :: Their Primitive Superstition
Our Noble Populace :: Their Backward Savages
Our Heroic Adventurers :: Their Brutish Invaders
Our Legal Embargo :: Their Illegal Blockade
Sorry, english is not my first language. I did not realize there was a strong difference between blockade and embargo. Thanks for the correction.
Though to be fair, there is currently an actual oil blockade run by the USA. And the previous embargo imposed sanctions on international entities dealing with Cuba, so it was not exactly 100% open even though technically you could sail there.