Yes, you are generally permitted to bring your own food and non-alcoholic beverages on almost all ferry services. Unlike airlines, ferries typically do not have strict "liquid" restrictions, allowing you to bring full-sized water bottles, sodas, and even prepared meals like sandwiches or salads. This is a common practice for budget-conscious travelers, as onboard cafes can be expensive. However, there are two major caveats: first, most ferry lines strictly prohibit bringing your own alcohol for consumption on board; any alcohol must usually be purchased from the licensed onboard bars. Second, if you are traveling on an international ferry (e.g., from the UK to France or between Caribbean islands), you must adhere to the customs and agricultural regulations of your destination. For example, many countries prohibit the entry of fresh fruits, vegetables, or meat products to prevent the spread of pests and diseases. Always check if you need to consume or dispose of your "fresh" snacks before you disembark at a foreign port to avoid fines.