What must you have besides a life jacket on a boat?

Besides a life jacket, you must have a sound signaling device, such as a whistle or horn, to alert others in case of emergencies. Additionally, a fire extinguisher is crucial for safety, especially if you have a motorized vessel. It's also recommended to have a first aid kit and appropriate navigation lights if you're operating after dark. Ensure you comply with local regulations, which may require other safety equipment.