3rd Gen Shoal Cave

In the Hoenn games, there's an area near Mossdeep known as Shoal Cave. In here, you can collect these useless items known as Shoal Salt and Shoal Shells. They serve no purpose other than being traded in for Shell Bells. If you collect four of each of the two items, you give them to an old man at the front entrance to get a Shell Bell. You can repeat this every day, unless your internal battery is dry. But, in OR/AS you can do it infinitely every day.

This is also the only location in the game where you can obtain a Snorunt, and you can only find Snorunt during a low tide. So, if you're replaying R/S/E and want one, and your internal battery is dry, set your in-game clock to the hours between 4 AM and 9 AM or 3PM to 7PM.

Did you do the small Shoal Cave "subquest"? I did it back when my internal battery wasn't dry. :') Shell Bells are actually pretty useful in battle frontier battles. And I did get Snorunt once, too. It's unfortunate how hard it is to get this Pokémon in RSE these days since my internal battery is sadly long dead.

No sadly because i had no idea this existed when i first played the game and when i replayed it my battery was long dead i have done it in oras though.

I collected a lot of Shoal Shells and Shoal Salt, but I only ever made one Shell Bell from them. In my Ruby and Emerald it's always high tide in the cave, whereas in my Sapphire it's always low tide all because of the internal battery running out.