IRAN IS GOING TO BLOW UP THE DYKES THAT KEEP THE WATER ON THE EARTH FROM FLOWING OFF. THE EARTH IS FLAT. This Has To Be True Because The Flat-earthers Have Found The Dykes. The dykes are not women tying to be men, either. So do not laugh.

Obviously flat-earthers have not been to the edge of the Earth to see the dykes that keep the water from flowing over the edge of the Earth. If they had they would realize that the dykes that keep the water on the Earth from flowing off are tall stories.

How long should it take to go from London To Tokyo via Seattle and back, if the Earth were flat?

If you believe the Earth is flat, buy an airplane ticket to travel from London to Seattle and Seattle to Tokyo and then back to London and learn the truth. 

If you cannot afford a ticket, here are the flight duration times:

London to Seattle, Canada  9hrs 50m duration +
Seattle To Tokyo, Japan 10hrs 15m duration = 20hrs 5 mins.

Tokyo to London, England 12hrs 25m duration

If the Earth were flat, the duration of the flight from Tokyo to London should be some 20 hours, not 12hrs 25m. This is because you would have to fly back and there are no shorter ways like flying around the globe.

Forget the nonsense. The Earth is a globe.

If you stand on a mountain peak you will always see the horizon at eye level. This will present as a circle. But the sky will present as a dome and meet the horizon. If you lie down on your back the sky will be flat. Odd but true.

Learn the truth about life.