🌊 Tide Guide
Everything you need to know about tides — from the science behind them to reading tide tables and staying safe at the beach
How Are Tides Formed?
The Moon and Sun both contribute to the forces that produce tides. The size and timing of a local tide also depend on coastline shape, water depth and the ocean basin; a fixed percentage does not describe every location.
When the Moon, Earth, and Sun are nearly aligned (new or full moon), tidal ranges are greatest — these are called spring tides. When they form a right angle (quarter moons), tidal ranges are smallest — called neap tides.
High Tide & Low Tide
High Tide: The time when water reaches a local high level. Greater depth may help at some entrances, but safe navigation also depends on currents, weather and port guidance.
Low Tide: The time when water reaches a local low level. Rocks or tidal flats may be exposed, but access and the returning tide must be checked before exploring.
Tidal Cycles
Tidal patterns vary by coast: semidiurnal areas have two highs and two lows each lunar day, diurnal areas have one of each, and mixed areas have two unequal highs and lows. A lunar day averages about 24 hours 50 minutes.
A repeated tide time often shifts from one solar day to the next, but local timing is more complex than a fixed daily offset. Check the prediction for your station instead of adding 50 minutes by hand.
Tides and Beach Activities
Low tide may expose rock pools or tidal flats, but the safe visiting window depends on local terrain, access and the speed of the returning tide. Check both the low and the following high tide times.
Daylight improves visibility on unfamiliar shorelines. Spring tides can expose more ground at low water, but the larger tidal range can also increase the risk of being cut off as the tide rises.
Tides and Navigation
Vessel movements depend on the port, charted depth, predicted tide, weather and official navigation guidance. A tide table alone is insufficient for planning a harbor entrance.
Tidal currents may matter to fishing and small craft, but suitable departure times vary by harbor and conditions. Follow local notices and current information rather than a universal flood-tide rule.
Spring Tides vs Neap Tides
Around the new and full moon, the Sun, Moon and Earth align — gravitational forces combine to create spring tides with the greatest tidal range: highest highs and lowest lows.
At first and third quarter moons, the Sun and Moon act at roughly right angles, producing neap tides with a smaller tidal range. The safest time for a beach activity depends on local conditions, not simply the lunar phase.
📖 How to Read a Tide Table
A tide table lists predicted high and low times and heights for a specific station. Heights are measured relative to a stated datum; chart datum is not always Lowest Astronomical Tide. Check the datum and units before comparing stations. NOAA explains common tidal datums.
What is tidal range?
Tidal range is the difference between a high and a low water level. It varies widely by location and day; compare predictions at the same station and datum rather than assuming all coasts have a similar range.
🦺 Beach Safety & Tidal Awareness
Before visiting a tidal shore, check both low and high tide times, local access advice and weather. Allow enough time to leave before the returning tide cuts off your route; there is no universal one-hour safety margin.
Never go alone to unfamiliar rock platforms. Wet rocks are extremely slippery. Wear appropriate footwear and be aware of local regulations — many areas have restrictions on collecting marine life.