Sea biscuit is a term that is often used to refer to a type of hardtack biscuit that was traditionally eaten by sailors on long sea voyages. While this term may be commonly used, there are actually a number of different synonyms for sea biscuit that can be used in its place. Some of the most popular alternatives include hard bread, ship bread, sailor's biscuit, and pilot bread. Other terms that can be used to refer to these types of biscuits include sea crackers, navy crackers, sea bread, and ship biscuits. No matter which term you choose, all of these synonyms are perfect for describing the staple food of sailors on long ocean voyages.