Why? Because there are sections of the sea that you can dive in that contain seaweed for you to search for wild Pokemon like Clamperl, and because you can find coloured shards that the Diving Treasure Hunter will trade for Evolutionary stones. You can also find things like pearls, which you can sell at a high price at a Pokemart.
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.
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.
Dive is not an HM in leafgreen however some Pokemon can learn it on there own, if you want to have a Pokemon with dive have the Pokemon that you want learn dive in ruby or sapphire or emerald then have them trade you it and now you can use dive but not outside of battle because its not an HM.
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
You can't unless you trade a Pokemon from Pokemon Ruby, Sapphire or Emerald and get a Pokemon that knows Dive. The HM Dive is not necessary in Pokemon Firered and is thus not avaliable. However, a Pokemon that knows Dive can be traded from Pokemon Sapphire, Ruby or Emerald version to Firered.can notI can't remember much, but I think you have to get it from Wallace or Juan.
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
simply press 'B' or go to pokémon list > *pokemon with 'dive' > DIVE
sorry NO. but you have to dive