you need to use a water type pokemon and teach it dive or use action replay
It said that you will dive....
You must beat the MossDeep City gym to use the HM for Dive.
You have to delete dive before you transfer it to platinum.
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!
In the sea, where the water is darker than the surrounding areas.
use dive go in the deep sea grass he will be in the grass
I think you get it after you get the gym badge that lets you use rock smash
Clamperls are found when you use Dive, and roam in the grassy-areas. ^_^
no sadly it can only be used in ruby, sapphire and emerald
Steve
the mossdeep cite gym has twin traners to get dive outside. and you get DIVE HM5 from steven at his house on Mossdeep City!
Since dive is not a HM in firered you will have to trade a Pokemon to a friend that has ruby, sapphire or emerald then using that game use the HM Dive to teach the move Dive to that Pokemon trade it back so firered can have that Pokemon again it will still have Dive however you cannot use it to dive underwater.