I have once again picked up CC3 and once again I am stumped by a desire to create a landlocked sea.

If I have an already created a land mass, how do I remove a section of it in the middle (without connecting to one of the boarders) so that the sea (template background) will show through? I am trying to avoid creating a higher sheet such as a lake or river.

It was suggested I use the MultiPoly tool, however everything I have tried using that tool, has simply erased the entire landmass. Below are the steps I tried using the MultiPoly tool (I will admit I am not sure I am using the tool correctly).

1. I already have a filled landmass, created using land default.
2. I created a second enclosed poly, in the shape that I want removed from the landmass.
3. I click MultiPoly, and selected the poly created in step 2.
4. Right click and select Do It

Result: The poly I created fills in with the color as dictated on the top bar, combining both the outline and the fill together and moves it to the sheet I also have displayed on the bar.

Issue: I am noob with CC3 and CAD, and I don't really have a clue what multipoly is doing. I have checked the help and google, but neither give a very good definition.

Wanted: I want to subtract the poly I created in step 2 from the landmass I created earlier, leaving the default sea underneith displayed. I want the outline of the new poly to basically be a new (internal) border for the land mass. Ie create a hole in the land mass.

Does anyone have any ideas? Furthermore, does anyone know of a tutorial that shows the effective and hopefully multiple uses of the MultiPoly tool? (bonus if it actually shows how to make a hole in an entity)