A new three-part series for BBC Two, Equator, charts a 25,000 mile-journey around the world. This dividing line between the northern and southern hemispheres has fascinated people for centuries, resulting in an abundance of myth, legend and hearsay.
BBC weather presenter and meteorologist, Phil Avery, separates some of the fact from the fiction.
Does water really flow down a plug-hole clockwise in the southern hemisphere and anti-clockwise in the northern hemisphere?
Is the moon "upside down" in the southern hemisphere?
And in equatorial regions is the climate always the same?
If you start drawing imaginary lines on a planet, I suppose there is bound to be endless scope for myths to develop.
But perhaps the greater degree of surprise comes from the knowledge that not all the myths date from ancient history.
Dare to express an opinion about water disappearing down a plug-hole anywhere near the equator, and you enter a world of entrenched opinion and scathing ridicule of your grasp of science.
Portuguese adventurers and explorers of the early 15th century would never have passed the headlands of Northwest Africa had they believed the myths of monsters and boiling seas which were so widespread in western Europe at the time.
Rep of Congo
Dem Rep of Congo
The "line-crossing ceremony" - a seafaring tradition dating back to the Middle Ages - commemorates a sailor's first crossing of the equator and is still practised - to an extent - aboard some naval ships today.
It was originally created as a test for seasoned sailors to ensure their new shipmates were capable of handling long, rough times at sea.
Traditionally presided over by "King Neptune and his Royal court", the ceremony was part of an initiation into "The Solemn Mysteries of the Ancient Order of the Deep".
In the 19th century and earlier, it was quite a brutal event and would sometimes involve sailors being beaten with wet boards and ropes, and then occasionally throwing these men overboard.
Night and day
There are some indisputable facts about the equator:
The region around the equator is the area with the world's greatest concentration of human poverty and natural biodiversity.
- Almost half the world's rainforests are concentrated on the equator in just three countries: Brazil, Congo and Indonesia.
- The Sun - in its seasonal movement - traverses directly over the equator twice each year, on the spring and vernal equinoxes.
- Locations along the equator experience the fastest rates of sunrise and sunset on the planet. The transition from day to night takes only minutes.
- The lengths of day/night time vary very little, while more northerly and southerly locations can vary enormously. Season-long days and nights are a feature of life at the poles.
While on the astronomical aspects of equatorial misconceptions, discussions have ranged over the moon's ability to turn upside down once across the equator.
Not a question that crossed this inquiring mind but, once again, choose your website with care and you too can become immersed in the subject.
To save you the bother though, the consensus seems to be that the Moon does appear to have such an ability, but this is the exception to a much more prevalent rule.
The direction in which water drains is the most debated equator myth
But this debate is nothing compared to the old chestnut of the water disappearing down the plug-hole in different directions depending on your hemisphere of choice.
I offer one line of argument only (although I am not sufficiently arrogant to believe that anything I write will settle this once and for all).
Water flows down the plug-hole in the direction it is introduced into a sink or drain.
The effects of Coriolis - when the rotating earth causes the winds to deflect to the right in the northern hemisphere and the left south of the equator - on baths of water, at whatever distance from the equator, is minimal.
Very large vortices are affected by Coriolis. The Coriolis force is too weak to affect a system as short-lived as a basin full of water.
Hurricanes and our more familiar areas of low pressure, which originate in different hemispheres, rotate in opposing directions.
From a meteorological perspective, the myth of the equatorial climate always being the same certainly needs to be dispelled.
Regular downpours feed the lush landscape in western Sumatra
Tropical areas along the equator can experience wet and dry seasons while other spots may well be wet for much of the year.
Given that the length of the equator is just short of 25,000 miles (40,000kms), there is obvious scope for variety.
Seasonal variation is supplemented by the influences of elevation and the proximity of an ocean.
Life at 5,790m on the slopes of Volcan Cayambe in Ecuador is very different to that on the Aranuka and Nonouti Atolls in the Gilbert Islands; both areas through which the equator passes.
Snow lies on the ground in Ecuador, but is in very short supply in the Gilbert Islands.
The extent of web debate over equator-related myths is astounding.
And whatever wonders scientific discoveries may hold, I am sure seafarers will continue to pay their dues to King Neptune as they cross the equator for the first time.
The elaborate and often amusingly degrading initiation rituals are a safer bet than falling foul of the King of the Deep.
Well, would you take the chance?
Equator: Episode One was broadcast on Sunday, 27 August, 2006 at 2100 BST on BBC Two.