1. What the information covers
Umimori is for learning about ocean science, safety and the environment. It provides general explanations. It does not assess safety at a particular coast, decide whether swimming is permitted, predict weather or sea conditions, or select a rescue method for an individual situation.
Diagrams simplify shapes, sizes, time and other conditions. Read each diagram’s explanation and limitations. AI-generated illustrative images are not photographs recording a real place.
They have not yet been checked by a safety specialist. Prioritise current official information and instructions from local operators.
2. Learning at school or home
You may print or project this site’s original writing and diagrams for non-commercial learning at school or home, with a source credit. Keep explanations and cautions with the diagrams, and avoid cropping that changes the meaning.
Source: Umimori, “Why do tides rise and fall?”
https://umimori.jp/en/learn/tides/
Before using material in a lesson, the person leading it should check the content, audience age and scope. Writing and images on external reference sites are subject to their rights holders’ terms.
3. Copyright, republication and commercial use
Rights in the content belong to the operator or the relevant rights holder. Giving a source credit does not automatically authorise republication on another site or redistribution as an asset.
Except for uses permitted by law, please contact us about republishing on websites or social media, modifying or redistributing diagrams, publishing in books, or commercial uses such as paid teaching materials or advertising. Include the page, purpose, destination and extent of use.
Ordinary links to the site do not require advance notice. Do not imply an official partnership, review or endorsement, or hide the source.
4. Limitations and updates
We consult sources such as public agencies and aim for accurate, clear content. We cannot guarantee completeness, currency or suitability for every situation. Reading an article does not guarantee that an activity at sea will be safe.
Content and structure may change as sources are updated or errors corrected. External sites are managed by their own operators. These statements do not exclude responsibilities the operator has under law.
5. Operator and corrections
The operator is surf life. This is not a continuation of the former volunteer organisation Umi-mori’s official site, and is not a public authority’s official website.
If you find an error or unclear explanation, see how to request a correction. Our editorial policy explains source checks, AI use and updates.
Created and updated: 20 September 2026