The entrance to Achao was easy--a long bay, wide-open to the north--but protected from all other direction--with a sandy bottom that got shallow slowly. I don't remember if it was Maria Olga or Google Earth that told me there was no danger from fish farms (which are very difficult to see at night) in the entry to Achao. After getting slowed down by a large amount of kelp that attached itself to the centerboard which took a long time to clear, we arrived after dark.
Other than the anchored boats with no lights (of which there were two) which forced some last-minute course changes, it was a very easy approach at night.