The Duchateau Isles are three low, wooded, coral islets, the largest of which is only three-fourths of a mile in length.
The two eastern islands are connected by a reef, partly dry at low water, and separated by a narrow passage from the smaller reef, surrounding the western island.

The southern, or windward margin of these reefs, presents a similarity to the barrier class by rising up suddenly from an unknown depth, with constant and very heavy breakers, but the northern, and at present the leeward portion, extends only a little way, with irregular and not well defined outline, and anchorage near it in from twelve to fifteen fathoms.

The three islands agree in presenting the same physical characters.
PLANTS AND ANIMALS.
They are margined by a beach of white coral sand, with occasional thin beds and ledges of coral conglomerate, succeeded by a belt of tangled bushes and low trees, after which the trees become higher and the ground tolerably free from underwood, with occasional thickets of woody climbers.

The cocoa-palm grows here in small numbers, usually several together, overtopping the other trees among which one of the Bombaceae (silk-cotton trees) and Pisonia grandis attain the greatest dimensions, having frequently a girth of twelve or fifteen feet, with a height of sixty or seventy.

A large-leaved Calophyllum is the prevailing tree of the island, and among the others I may mention a Myristica and a Caryophyllum, neither of which, however, are of the species furnishing the nutmegs and cloves of commerce.
Of mammalia a large Pteropus, or fruit-eating bat, was seen once or twice, but no specimen was procured.