On the southern coast of the island of Cuba, at a few miles from land,
Springs of Fresh Water gush from the bed of the Ocean, probably under
the influence of hydrostatic pressure, and rise through the midst
of the salt water. They issue forth with such force that boats are
cautious in approaching this locality, which has an ill repute on
account of the high cross sea thus caused. Trading vessels sometimes
visit these springs to take in a supply of fresh water, which is thus
obtained in the open sea. The greater the depth from which the water is
taken, the fresher it is found to be.
“THE BLACK WATERS.”
In the upper portion of the basin of the Orinoco and its tributaries,
Nature has several times repeated the enigmatical phenomenon of the
so-called “Black Waters.” The Atabapo, whose banks are adorned with
Carolinias and arborescent Melastomas, is a river of a coffee-brown
colour. In the shade of the palm-groves this colour seems about to
pass into ink-black. When placed in transparent vessels, the water
appears of a golden yellow. The image of the Southern Constellation
is reflected with wonderful clearness in these black streams. When
their waters flow gently, they afford to the observer, when taking
astronomical observations with reflecting instruments, a most excellent
artificial horizon. These waters probably owe their peculiar colour to
a solution of carburetted hydrogen, to the luxuriance of the tropical
vegetation, and to the quantity of plants and herbs on the ground over
which they flow.--_Humboldt’s Aspects of Nature_, vol. i.