first you have to get the dive move from steven at his house.then you have to beat the gym leaders in mossdeep city.finnally you dive where the water is black space and then you,ll find yourself underwater.hope you guys can do it.
Steve
you first go to steven to get dive and dive dvie
Moosdeep City.
You need to dive somewhere then in dive in a different location hope this helps
The HM Dive is given by steven at his house in mossdeep city.
It said that you will dive....
sorry NO. but you have to dive
on the route under mosdeep
simply press 'B' or go to pokémon list > *pokemon with 'dive' > DIVE
in mossdeep city steven gives it to you
Underwater by using dive
You have to delete dive before you transfer it to platinum.