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A swim and a patch of grass can be enough for a summer afternoon. Start with a published bathing spot or public lido, then check changing rooms, toilets, shade and swimming supervision. A quiet-looking cove is not automatically public access.
Read local notices and consider water and weather conditions before entering. Keep children closely supervised and choose an entry you can leave comfortably. Bring sun protection, a towel and dry clothes. Check the return bus or boat before settling in, especially if you are staying elsewhere.