Heading west from Route 130, Route 131 passes by a pair of Trainers (in Emerald only) before coming to the mouth of the winding channel that leads to the Sky Pillar. In Pokémon Ruby and Sapphire, there is a female Swimmer west of the channel mouth. In all Hoenn-based Generation III games, there are two more Swimmers to her west.
Northwest of the second Swimmer in this group is a lone Swimmer in the middle of the route. To his northwest is a Sis and Bro Trainer team. South of the duo in Pokémon Emerald is yet another Trainer.
Pacifidlog is a short paddle to the west from this point.