Navigation is a significant advance in any C-evo game where there are significant areas of open sea, because naval units that do not have the Navigation feature cannot enter such tiles.

Navigation, one of C-evo's "Early Advances" (not needing Science)


Astronomy and Seafaring
Allows or enables: Magellan's Expedition; Navigation (Unit Advance) (C-evo)

Has military or other value: Naval unit modules for weapons and armor add 4 to strength and all naval modules cost no less than 10

Further advances
that require it:

Amphibious Warfare
See also: Navigation (Unit Advance) (C-evo)