You get it in Mossdeep City. Hope I helped :)
You get it from Steven in Mossdeep city.
In Mossdeep City, Steven will give it to you.
You get Dive from steven not may.
You cannot get HM Dive in Pokémon LeafGreen.Since Dive is not an HM in leafgreen the only way to get one of your Pokemon to learn Dive is to trade it to ruby, sapphire or emerald then teach it Dive using the HM then trade it back to leafgreen.
Hidden Move 8.
Steven will give it to you
there's no hm dive in firered.so that means you can't find it.but you can find it in Pokemon ruby,sapphire,emerald and more.
in Sapphire, Ruby and Emerald, you can get it in Steven house locate in north west of the pokemon center in Mossdeep city. For other version, i don't think you can
there is no dive HM in DP but the water related ones are surf and waterfall
use the hm dive
after defeating the 7th gym leader
You can't get dive in fire red, however it is HM 8 in Ruby, Sapphire and Emerald.