How do i make a map like (water wars)????

Hi... Does ani1 knows how to make water wars's under water lane. i'll be glad if u tell me for i have that missing stuff in my map.. thx alot if u guys know

Tutorial:
http://www.wc3campaigns.net/showthread.php?t=80968

And if it is something else you need to ask about, plz give more info.

example. illidan is above water hes at a island not underwater he castes submerge at water it takes him down to another map which i think, conclusion illidan cast submerge at island, he goes dwn to underwate.