Bus or rented car to the aquarium (allow ~1.5–2 hours from Naha); aquarium opens early (commonly 8:30AM–6:30PM, summer hours can extend—check official site).
Beautiful mossy forest made famous as inspiration for Studio Ghibli; trails typically well-marked and popular—park opening hours often begin ~8:30AM so verify start times.
Iconic ancient cedar tree; the full hike is strenuous and can take 10+ hours round-trip—many visitors choose a guided tour or a shorter alternative if on a budget/time limit. Check trailhead opening and guided tour availability in advance.