It's called Meremanoid and it has some incredible art and a low-poly underwater world to explore! Gosh, I swear you can explore the PS1 library for your whole life and still come across magical little surprises like this.
This is rad! I like that when you win a battle there's a voice-over saying "YOU ARE OUTSTANDING WARRIORS. THIS BATTLE HAS GIVEN YOU VALUABLE EXPERIENCE." as your xp gauge fills after battle. More RPGs should have this crucial feature.