While sailing away from Rio de Janeiro, Darwin sees a very large group of porpoises numbering in the hundreds. The Beagle enters the Plata estuary where seals and penguins surround the ship and make noises that resemble cattle. The water is very luminous. St. Elmo's fire, an atmospheric electrical phenomenon, makes the yardarms glow. Lightning flashes in the sky. Darwin notices in the daylight the muddy river water floats atop the denser salt water, creating interesting swirls of brown and blue as the ship passes through the mouth of the Plata River.
The author stays ten weeks in a small town named Maldonado at the mouth of the Plata River. The town is laid out with streets running at right angles and having a central square. The primary industries involve cattle, hides.....
