There's not much to do here just yet, except stop by the Stone House. Battle a few trainers if you like and continue on to Mossdeep City.
Relicanth is found underwater in Route 124 in Pokémon Ruby and Sapphire. Though it is a fish Pokémon, it cannot be caught with a fishing rod. It is slightly tough to catch; 2 or 3 Ultra Balls might get wasted, and Net Balls and Dive Balls do not work well.
Along with Wailord, Relicanth needs to be present in the your team to remove the seals from the hiding places of the Legendary Pokémon, Regirock, Regice and Registeel.
- Blue Shard - requires dive, found by surfacing in southwest area
- Yellow Shard - requires dive, found by surfacing in northeast area
- Red shard - requires dive, found by surfacing at in northwest area
- Carbos - hidden in clearing in seaweed patch in the S-shaped trench
- Heart Scale - hidden in the dark spot beneath the dive spot closest to Mossdeep City
- Heart Scale - hidden in the dive spot in the center of the route
- Calcium - hidden in the dark spot beneath the north-central dive spot
- Pearl - hidden in the dark spot below the second dive spot northwest of the Treasure Hunter's house
- Big Pearl - hidden in the dark spot directly below the dive spot southwest of the Treasure Hunter's house
- Green Shard - hidden in a seaweed clearing below the small dive spot near Lilycove City