“Great day on the water” may capture a mood, but it leaves a photograph doing all the remembering. A useful caption adds something the picture cannot reliably explain: where the scene was observed, what happened just before it, or why you chose that frame.
Begin with the visible scene
Write one plain sentence describing what you can see. For example: “Two white boats sit beyond the harbour wall, with their reflections broken by the surface.” This is an illustrative caption, not a report from a particular harbour.
Keep vessel names, classes and technical descriptions out until you can verify them. A confident-sounding label is not an improvement if it identifies the wrong thing. The same applies to describing a manoeuvre from a single still frame.
Add context from your own record
Your notebook may provide the date, the public viewpoint or the reason you stopped. Add one detail that matters. “Photographed from the eastern promenade after the rain cleared” is useful only if your notes actually support it.
When posting an older image, distinguish the photograph’s date from the publication date. A new upload should not accidentally present an old scene as current conditions. Avoid turning a calm-looking surface into a claim about safe sailing weather.
Separate caption and image description
A caption can carry the story around a photograph. Alternative text should explain the image’s relevant visual information for someone who cannot see it. They may overlap, but neither needs a string of repeated search phrases.
Try reading your caption without the photograph. Then look at the photograph without the caption. If both merely repeat “beautiful boat”, add a specific observation. For a place to retain those details between visits, use a simple sailing journal.