How to merge scenes in Unity?

I am making a game and the island would be very big.........while making the layout of the island I got an error saying that i've used to much of the hill or hump making thingy.....so i decided that i'll make it in parts and them merge them into one so that when the player is walking as normal he can move from one scene to another without even noticeing it. By the way I am NOT talking about level and I'm planning on making one similar to zelda( big area,fight outside)

the Application class let's you do a couple of things with scenes, e.g. load scenes into the current scene, take a look at that - Application.LoadLevelAdditive

http://www.unifycommunity.com/wiki/index.php?title=LoadSceneAdditive

At Apex we have used quite some time on making a solution to your problem.

The initial problem we couldn't get around was our memory footprint when loading/unloading scenes with terrains. The solution to that problem was to use asset bundles and make the bundles as small as possible in combination with an asset bundle reference counter.

We now chop terrains into tiles (mesh + terrain collider), LOD the tiles and load/unload them smoothly. However, we could use other kinds of objects as tiles.

Our tool is called ColdScene and you can read about it and try out: ColdScene 0.1 ... ColdScene 0.3.1

Hi there, we at Defective Studios have the tool for you! If you want to merge two scenes side-by-side, check it out!