Guernsey · coast guide
Understanding the coast of Guernsey
This guide explains the coast of Guernsey on the English Channel; calculations, observations and product limits remain distinct.
Read a local tide
Times and heights depend on the port, datum and station timezone. St Peter Port, Sark, Alderney lie on . These sectors are not one reference: displayed time must remain attached to the selected place and its Europe/Guernsey timezone. A value from another place cannot be carried to a nearby beach. Mareloa preserves the source and timestamp of its data but does not replace the national hydrographic reference.
Tidal range and coast
Even on a short coast, a local reference remains essential. Coastal shape, bays and exposure distinguish these places. A time, height or condition from one cannot be moved to another; always begin with the source attached to the named place. Tidal range is the vertical difference between low and high water. Bays, depth and coastal shape change it, so one astronomical cycle does not create the same range everywhere. Mareloa creates no national coefficient for Guernsey and infers no access from one number.
Prediction, model and observation
The OpenStreetMap geographical catalogue is non-exhaustive and provides no health status. The review identified no stable national authority; OpenStreetMap remains only a geographical reference, without health status. An astronomical prediction calculates a periodic component. A model adds assumptions; an observation is a measurement at a station and time. Wind, pressure, waves and geography can change actual level. These categories remain separate and missing evidence never becomes reassuring.
Plan a coast visit
Access, health notices, restrictions and signs are local. Check the competent authority and information at the place before a visit; this guide neither authorises an activity nor provides navigation instruction. Use this guide to understand provenance, not to decide an activity. Restrictions, health notices, access and signage are local and can change. Consult the competent authority and on-site information; Mareloa is not a navigation tool.
Reviewed source
This page cites and links to this public reference; it does not reproduce its tables.
Reviewed 2026-09-11.