What type of light should a rowboat use after dark?

A rowboat should use a flashlight or lantern after dark to ensure visibility and safety. The purpose of these portable light sources is to illuminate the surroundings, allowing the operator to navigate safely, and to signal presence to other vessels. Flashlights and lanterns are practical choices for smaller boats like rowboats, as they provide direct light without requiring mounting or installation, making them easy to use.

Using a headlight is less appropriate for a rowboat because these are typically designed for use when speed or a direct beam is needed, which may not be ideal for slower-moving or stationary vessels. Underwater lights are primarily used for illuminating the water beneath a boat and are not used for general navigation or visibility for other boats. Flares are emergency devices meant to signal distress and should not be used for regular navigation purposes, as they carry a specific function for attracting help in emergencies.