# If I wanted to circumnavigate the world by water (boat) what is the shortest total distance around?

I'm looking for the total number of meters you would have to travel around the world if the entire voyage was on water. Thru canals counts, as well as any waterway that gets me around the world. I don't want circumference of the world, but travelable distance.

I ask this not because I'm going to actually sail or boat around the world, but because I've been rowing for exercise for 17 years. I've accumulated 35,000,000 meters in that time and estimate that I've 'rowed around the world' when I get to about 41,000,000 meters. Is that correct?

• Should we presume you mean the shortest equatorial circumnavigation? Jan 24 '20 at 15:00
• This might sound like a silly question, but what's your definition of circumnavigation? Jan 24 '20 at 15:04
• I take circumnavigation to mean traveling around the world near the equator entirely on water. I understand that if there was no ice I could travel north-south on water which may be a shorter distance than near the equator if we assume that the earth is not a perfect sphere
– Bob
Jan 24 '20 at 15:39
• Here's someone who's actually done it! around-n-over.org/circumnavigation.htm Jan 24 '20 at 15:40
• I assume use of the Panama Canal to get through North and South America. My geography is not good enough to figure out the route to the Mediterranean Sea and the distance North or South extra you would have to travel to have the entire voyage on water.
– Bob
Jan 24 '20 at 15:43

There three reasonable ways to approach this.

1. Use a tool such as OpenCPN to plot your desired course.
2. Use the Jules Verne Trophy rules at approximately 40,000km.
3. Use the Earthrace route, which transits the Panama and Suez canals at approximately 45,000km.

Using Google Maps, I get about 40850 km (Gibraltar - Suez Canal - Red Sea - around the tip of Sri Lanka - through the Malacca Strait - North of Borneo - South of the Philippines - straight across the Pacific - Panama Canal - straight across the Atlantic), so 41000 km is a good approximation.

I’m on my mobile right now, I’ll try to refine this when back on the desktop. There may be alternative ways around Indonesia that may shave off a little bit.

Note that this is using straight lines just avoiding obvious landmasses, not taken into account anything special like lanes of traffic in busy place and of course not taking into account prevailing winds or currents which would be relevant for sailing... or rowing.

• Which straight lines? Straight lines on the mercator projection mapm Loxodromes? Orthodromes? Jan 25 '20 at 9:56

The original definition of "meter" was a distance such that there are 10,000,000 of the between the equator and the North Pole. Since that is one fourth of the way around the Earth, the total distance would be 40,000km. That is what's known as a "normal" route (being perpendicular, or normal, to the equator); an equatorial route would be longer. Also, the current definition of the meter is slightly different, but 40,000km is still accurate to a few kilometers for the normal route.

Longer still would be an actual route, as there is generally land in the way. Of course, if you go to the North Pole, a route that crosses all meridians can be arbitrarily small. Thus, defining just what constitutes a "circumnavigation" tends to be complicated, with such stipulations as the route include at least one pair of antipodal points.