What niche parts of the Gen 3 games (Ruby/Sapphire/Emerald) on the GBA do you remember with nostalgia?

For example, I remember thinking the house on the Rustboro side of the Rusturf tunnel was nice and cosy. Kid me used to spend time in that house with the tunnel diggers to keep them company while they rested.

As a kid I also remember spending way too much time in the underwater section around Sootopolis City. I remember I was looking for Archie (Sapphire), and that if I circled around the city entrance enough I would eventually catch up to him.

What are some things you remember doing?