How useful are explorers in AOE3 in the late-game?

It depends on the type of civilisation you choose. If you choose European civs, then maybe a few one shot kills. read more

The Capitol has quite good upgrades for the explorer, but you only have 1 explorer (or maybe 2 in Asian Dynasties). Still, it's your choice to use it in your army, it doesn't give a great advantage, but it may do something (the only problem is that he gives a decent amount of xp to your enemy when he dies). read more

Since I've been playing the game, I've noticed (I could say all of us) that a big difference from AOE3 and AOE2 is the fact that you have an explorer (like a hero, or leader) that does much of the early work in the game. read more

The Explorer is a unique Hero unit that is available for all European civilizations in Age of Empires III. The Explorer is a very strong Unit that explores the uncharted areas of the map and also provides economical and military benefits for your growing colony. read more