Make sure you bring a camera to capture the spectacular cascades of Salto do Coro. If it's raging, you may be able to feel the mist on your skin.
You'll have no end of sightseeing choices when visiting Mondonedo. Salto do Coro is an ideal place to begin here, but there are plenty of other worthwhile spots to visit. Mondonedo Cathedral, San Salvador Monastery, and Cathedral Plaza are near the cascade of water and will round out your day nicely.