The currents have negligible difference from surrounding water.
The Gulf Stream off of the coast of Florida, and the Loop Current in the Gulf of Mexico are significantly warmer than the surrounding water, while the Labrador Current off of the eastern coast of Canada is significantly colder than the surrounding water. The East Australian Current is significantly warmer than the surrounding water.
These temperature differences make the boundaries of the current noticeable because the water color will change and the nature of the animals that will be seen.
And how do they avoid a hundred different ships all sailing along the same route at once?
Well, over the area of a thousand mile voyage, there is plenty of space between vessels. Even in the more busy shipping channels (Dover Strait or Gibraltar), you try and leave at least a half mile between vessels. For close quarter situations, there are the nautical rules of the road that dictate who has the right-of-way.
Yes, and because of the difference in the motion of the RE sun and the FE sun, the boats must be travelling faster on a FE to observe the same effect.
Does the FE Sun have a different apparent position each day than the RE Sun? Are we talking reflections off of "sky mirrors" again?
Fish like to swim in the wake of fast-moving vessels, often close enough to nudge the vessel itself. The collective force of a lot of fish all nudging the vessel causes it to move faster.
Well, it is good to know that FE is driven by observations of the world around them. When a discussion about simple geography, not even something complex like physics, comes down to having to be explained by "little fish," I can see why the FES has trouble convincing people that the world is flat.