I woke up at 4am to what sounded like something straight out of the deep. Very eerie, especially when it's pitch black, the windows are open (just screens) and you hear this noise (picture it 20 times louder). After I closed the windows and slept for another hour (daybreak in Costa Rica), I got up to see these tiny little creatures. I learned later that they are the second loudest animal based on size. The Gray Whale is #1.