The latest SketchUp software lets you model your own underwater world! Just download SketchUp, go to 'Window' then 'Preferences'; choose 'Extensions' in the left column; toggle on 'Google Earth Ocean Modeling'; then Hit OK.

Next import desired terrain from Google Earth, then choose 'Get Current View' in SketchUp. If you get 'Camera altitude too high' warning, just move closer to ocean floor. Next, under “Plugins” menu, select the ocean floor or the surface to place your model. If you want to be in-between the ocean floor and the surface of the water, choose 'Model on Ocean Floor' and place your model above the terrain. Last, choose 'Place model' in Google Earth, view your model, if you’re satisfied, load it onto the 3D Warehouse by selecting 'Share Model' and it may show up in the 3D Buildings layer.

Source:→ Google Latlong Blog