Overproof rum is any rum that contains more than 50% alcohol by volume, meaning over 57% ABV. It is also known as Navy Strength rum, and historically, it was used by the British Royal Navy as a way to ensure that the rum they were being served had not been watered down. Overproof rum is more potent than regular rum, and it can add complexity and nuance to cocktails due to its higher alcohol content. However, not all overproof rums are created equal, and some may taste harsh if not made well. Overproof rum is also used as a float in certain shots or on top of desserts where it can be set aflame. Some popular brands of overproof rum include Wray & Nephew Overproof, Lemon Hart 151, and Goslings 151.