From the neighbourhood of Torres Straits to about the Tropic of Capricorn,
extends, at a distance of fifty to a hundred miles from the shore, an
enormous bed of coral, named the Barrier Reef. There, untold millions of
minute insects are still noiselessly pursuing their toil, and raising fresh
structures from the depths of the ocean. Neither is this jagged belt --
though deadly to the rash mariner -- without its uses. In the first place,
a clear channel is always found between it and the mainland, in which no
sea of any formidable dimensions can ever rise, and now that modern surveys
have accurately indicated where danger is to be found, this quiet channel
is of the greatest use to the vessels frequenting that portion of the
ocean, for they avoid the whole swell of the broad Pacific, which now
thunders against and breaks harmlessly on the huge coral wall, instead of
wasting its fury on the coast itself. In the second place on the Barrier
Reef is found the 'Holothuria', from which the 'beche-de-mer' is prepared.
It is a kind of sea-slug, averaging from one to over two feet in length,
and four to ten inches in girth. In appearance, these sea-cucumbers are
more repulsive, looking like flabby black or green sausages, and squirting
out a stream of salt water when pressed. But despite their disgusting
appearance, they are a most valuable cargo, from the high price they fetch
in the Chinese market, where they are a much-esteemed delicacy. The vessel
that goes in quest of 'beche-de-mer' takes several expert divers -- usually
Kanakas, or South Sea Islanders -- and having arrived at the ground they
propose fishing, a sort of head-quarters is established on some convenient
island, where vegetables are planted, to stave off the scurvy that would
otherwise soon attack the adventurers. This done the little vessel
proceeds to the edge of the reef, and begins work in earnest.

The sea-slug is found buried amidst the triturated sand, worn away by the
constant play of the waves, and only the experienced and keen-eyed Kanakas