The correct answer to this open question is the following.
The two bodies of water that the British navy blockade in the war of 1812 were the Gulf of México and the Atlantic Ocean.
According to historians that are specialist in this topic, the War of 1812 was the product of many things. For instance, British warships interrupting American trade, the impressment of United States sailors by no meaningful reason, English soldiers instigating Native American Indian tribes to attack American citizens in the Canadian borders, among others. On of, the strategies used by the English troops to take advantage of the hostilities was to block the two big bodies of water: the Gulf of México and the Atlantic Ocean.