Inland Kerbal Space Center
From Kerbal Space Program Wiki
The second Kerbal Space Center is a second spaceport located North-West of the main space center. It is not possible to build and launch rockets from this space center and as it doesn't have a runway it isn't possible to start space planes their either.
It is located in a H-shaped valley with a smooth surface so the best way to reach the second center is to fly there by plane.
Third Space Center
The third Kerbal Space Center is a landing strip, hanger and, command center located on the largest of the string of islands east of the main Kerbal Space Center. The landing strip has a grass-like texture to make the Space Center harder to find from the air.
