Undersea Mines (CTP1)

is a tile improvement in Civilization: Call to Power.
==Gameplay==
Undersea mines are massive mineral mines that create an additional +30-50 and +5 when worked. This improvement takes two turns to build and, depending on the terrain, costs 400-600 PW. 
==Great Library entry==
As mineral sources dried up, miners turned to the sea. Undersea mining proved even more dangerous than surface mining. Many of the early miners suffered tragic fates as technology lagged behind demand. Slowly, governments established laws prohibiting undersea mining until new technologies could provide workers with basic safety.