Ok, I know that once you are in hindering terrain, you can move freely through it, but what If there are 2 different types of hindering terrain next to each other. For example, on the Indy map outdoors, there are rocks that are adjacent next to the water. I have a char. on the rocks. Could I move freely into the water, or would I have to cut my speed in half?

That's not actually true.

First, when a character enters hindering terrain from non-hindering terrain it must stop its movement. (Unless it has a power or ability that ignores the effects of hindering terrain on movement.)

Second, if a character begins its movement in hindering terrain...that movement is halved. (Again, unless it has a power or ability that ignores the effects of hindering terrain on movement.) This is regardless of whether the character intends to remain in hindering terrain.

Different types of adjacent hindering terrain are still considered continuous hindering terrain. So a character would not need to stop when it moved from one type of hindering terrain to another type. For example, a character would not need to stop if it moved from rocks to water. Remember though that because the character began its movement in hindering terrain, on the rocks, the movement is halved regardless of where the character moves. Even if it stays entirely in hindering terrain, its movement is still halved.