🌊 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?
Tides are caused by the gravitational pull of the Moon and Sun on Earth's oceans. The Moon's gravity is the dominant force, accounting for about 68% of the tidal effect, with the Sun contributing the remaining 32%.
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 moment in a tidal cycle when water reaches its highest level. Water depth is greatest, making it safest for large vessels to enter and exit harbours.
Low Tide: When water reaches its lowest point. Reefs, rock pools and tidal flats are exposed — ideal for beachcombing, rock pooling and marine biology.
Tidal Cycles
Most coastal areas experience semidiurnal tides — roughly two high tides and two low tides every 24 hours, with a cycle of about 12 hours 25 minutes.
Because of the Moon's orbital motion, tides shift approximately 50 minutes later each day. Some regions (like the Gulf of Mexico) experience diurnal tides — just one high and one low tide per day.
Best Time for Beach Activities
The best time for rock pooling, shell collecting or exploring tidal flats is 1–2 hours either side of low tide, when the maximum area of the seafloor is exposed.
Prioritise daytime low tides (6am–6pm) for safety and visibility. Spring tides (around new and full moon) produce the lowest lows — ideal for discovering rarely-exposed marine life.
Tides and Navigation
Large ships with deep drafts must enter and leave ports around high tide, when water depth is greatest. Strong tidal currents during ebb tide can affect small vessel handling.
Fishing boats typically depart on a flood tide (incoming) and return before the next flood. Planning around tidal currents saves fuel and improves safety.
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 pull at right angles, partially cancelling each other out — producing neap tides with smaller tidal ranges. The best beach activities happen during spring tides.
📖 How to Read a Tide Table
A tide table lists the times and heights of high and low tides at a specific location. Heights are measured from the Chart Datum — the theoretical lowest astronomical tide at that location. The lower the number, the more of the seabed is exposed.
What is tidal range?
Tidal range is the difference in water height between high tide and low tide on a given day. The Bay of Fundy in Canada has the world's largest tidal range, exceeding 16 metres. The Mediterranean Sea, by contrast, has almost no measurable tide.
🦺 Beach Safety & Tidal Awareness
Always check the day's low tide time before heading to the beach. Plan to arrive at least 1 hour before low tide, and always return well before the tide turns. Incoming tides can move surprisingly fast and cut off escape routes.
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.