Moblie Submerged Units

[The General]

Any advice on how to make units submerge like the Naga yet still able to move? any work around or something like that.

 

[Wietlol]

You can make the unit's slightly hovering over the water using flying height and edit the model to lower it back to sea level.
Then you can set the flying height to 0 and the unit is under water.

 

[Eagle XI]

Use bear form, adjust submerged unit to have movespeed and give ghost or perma invis ability.