get a water Pokemon yhe TM dive and well dive under the water
Relicanth are found on the seafloor of the ocean(rare). You must have a Pokemon that learns dive though.
get rayquaza
You find them at the bottom of the ocean when you use dive, but there rare, so you won't find them very often.
Yes, Clamperl can be caught in Pokemon Emerald. You have to have a Pokemon that knows the move Dive, which can be taught through HM08 - Dive. HM08 is found in Steven's house in Mossdeep City, but only after you have beaten the city's gym leaders. Clamperl can be caught on routes 124 and 126 underwater (use Dive on the dark spots in the ocean).
You have to have a Pokemon in your party which know the HM Dive. Surf onto water then go to your party, select the Pokemon that knows dive, and click on Dive.
You get the abilty to use the move Dive from Tate and Liza in Mossdeep and then you can teach your Pokemon to Dive! X3 POKEMON-1001
to get a heart dive
Use dive.
You get Dive from steven not may.
You can get Dive in Pokemon Emerald by going to Mossdeep City and ensure you check all the houses.
you can find dive balls at the mossdeep city pokemart
You can catch it when you use dive.