Where are the world's largest tidal ranges?

Table of Contents

• What is a Tidal Range?
• What Factors Affect a Large Tidal Range?
• Largest Tidal Range - Bay of Fundy, Canada
• Second Largest Tidal Range - Severn Estuary, UK
• Frequently Asked Questions

Summary of Highest Ranges

There are several locations across the world with high tidal ranges. In this article, we'll explore two largest and find out what makes them so different. Before we do this, we need to know what a tidal range is.

What is a Tidal Range?

A tidal range is the difference between a high tide and its corresponding low tide in a given area (or vice versa). As we know, the moon has the biggest influence on the tide frequency and range. You can find out how the moon affects tides here; the largest tidal ranges occur during spring tides. The spring tides, and therefore their effect on the tidal range, are increased when a spring tide coincides with the equinox. This happens on Earth around 20 March and 23 September.

What Other Factors Affect a Large Tidal Range?

Large tidal ranges occur in coastal locations, where the topology of bays and estuaries affect the tidal range. Typically, narrow funnel-like inlets, combined with a shallow seabed traps water at a high tide and creates a large draw as the tide goes out.

Next, areas with natural resonance increase wave height, which in turn increases tide heights. Finally, the combined alignment of the Sun, Moon, and Earth during a spring (or King tide for particularly high spring tides) results in large variations between a high and a low tide.

Put these three key factors together, and you get an area with a large tidal range.

Largest Tidal Range - Bay of Fundy, Canada

Located between the landmasses of New Brunswick and Nova Scotia, the Bay of Fundy has an average tidal range of a staggering 16.3m (53ft). The entrance to the bay narrows, creating a natural bottleneck, resulting in a high range. The semidiurnal tide (where there are two high and low tides daily, read out about semidiurnal tides here) occurs in the Bay of Fundy 6 hours and 13 minutes apart.

The mouth of the bay sees 115 billion tonnes flow in and out of it twice a day. The highest tide ever recorded occurred in 1869. The Saxby Gale, a tropical cyclone hit the Bay of Fundy between 4th and 5th October killing at least 37 people. During the Saxby Gale, the water level rose to 21.6 m (71 ft).

Above are the tide times for the next couple of days for Ile Haute in the Bay of Fundy, Canada.

Second Largest Tidal Range - Severn Estuary, UK

Located between the landmasses of England and Wales, the Severn Estuary is the point at which the river Severn, Great Britain's longest river, flows into the Bristol Channel. The average tidal range for the Severn Estuary is 15m (50ft). As with the Bay of Fundy, the high tidal range in the Severn Estuary is the result of tidal funnelling by the English and Welsh landmasses.

The Severn Estuary experiences a phenominon called a Tidal Bore, where the rising tide moves into the Severn Estuary and the surging water forces its way upstream in a series of waves. The Severn Bore is popular with surfers, creating among the longest surfable waves in the world. Local man, Steve King holds the record of 7.6 miles (12.2km) of stand up surfing on the severn bore in March 2006.

A storm surge in January 2014 saw the tide reach 3.58m (11ft) higher than the mean average for the region.

Frequently Asked Questions

Where is the largest tidal range in the world?

The largest tidal range in the world is found in the Bay of Fundy, located between Brunswick and Nova Scotia in Canada. Its narrow, long bay formation, shallow seabed, and position combine to give it the largest tidal range in the World.

How big is the largest tidal range in the world?

The largest tidal range in the world, found in the Bay of Fundy, Canada, has a typical maximum tidal range of 16m between the highest and lowest tides.

What causes a large tidal range?

Three factors combine to produce the world's largest tidal ranges. Funnel-like bays and estuaries with shallow seabeds trap water at high tide and create a large draw when the tide goes out. Next, the natural resonance of the sea increases the height at high tide. Finally, the alignment of the sun, moon, and earth at a spring tide creates the largest difference between a high and low tide.

What safety risks come with large tidal ranges?

Large tidal ranges mean that the sea rushes in at an incredibly fast rate as the tide comes in. The reverse is also true, where as the tide goes out, it does so at an equally fast pace. This catches people out, so extreme caution should always be taken in areas with a large tidal range