M. Ehrenberg, while navigating the Red Sea, observed that the red
colour of its waters was owing to enormous quantities of a new animal,
which has received the name of _oscillatoria rubescens_, and which
seems to be the same with what Haller has described as a _purple
conferva_ swimming in water; yet Dr. Bonar, in his work entitled _The
Desert of Sinai_, records:
Blue I have called the sea; yet not strictly so, save in the far
distance. It is neither a _red_ nor a _blue_ sea, but emphatically
green,--yes, green, of the most brilliant kind I ever saw. This is
produced by the immense tracts of shallow water, with yellow sand
beneath, which always gives this green to the sea, even in the
absence of verdure on the shore or sea-weeds beneath. The _blue_ of
the sky and the _yellow_ of the sands meeting and intermingling in
the water, form the _green_ of the sea; the water being the medium
in which the mixing or fusing of the colours takes place.