I love the idea and movement, it makes me feel all cozy and happy, I'm just yet lost and unsure if this is alrady the full version or no, but it's pretty sweet! Are those rocks movable or not at all?
You can break them. You gotta reincarnate from the menu into the horned-fish and then grow enough to unlock the charge skill. Then become small again by reincarnating back into the horned fish (or basic fish) and swim down. Process from there isn't too different.