If there is a waterfall or rapids than you couldn't go swimming in the river
Conformal maps! It is a transformation that preserves local angles.
In distance, it's something like maybe 245,000 miles ... corresponding to the
several Apollo missions during which a Command and Service module entered
lunar orbit and swung around the back side of the moon with astronauts aboard.
The farthest from Earth that a human has ever gone <em>and walked on solid ground</em>
is roughly 238,000 miles, corresponding to the six Apollo missions that landed
six pairs of astronauts on the near side of the surface of the moon, between 1969
and 1972 .
