You need to get the HM dive from Steven in Mossdeep City. Then you will have to beat the gym leader in Mossdeep City. Then you will be able to use the HM dive. And you find the dark spots in water while surfing. Use dive. And to resurface. Use dive again!
you first go to steven to get dive and dive dvie
Classified.
After you find the submarine you use dive up to the surface.
About 2 Kilometres
like 11,000 meters
The whale is flexible. The submarine is not, and is therefore subject to crushing from the pressure.
200 ft
The process of a submarine to move from the surface of the ocean to a position underneath the surface is called a dive. This is accomplished by allowing water to fill the tanks of the submarine, the heavy water pressure now inside the vessel now will force it to sink below the surface, thus a "dive".
The proper submarine/naval term is the Helmsman, who controls the rudder and dive planes.
You have to dive underwater and find a submarine.
you dive at route 128 by sootopolis city