The western side of Vansittart Bay is formed by a peninsula, the extremity of which is Cape Bougainville; the northern part of this land is fronted by a reef, that extends round it for three miles from the shore, but the western side appeared to be of bold approach.  The reef commences at Cape Bougainville, and trends round to Point Gibson, where it terminates.  This part of the coast is fronted by extensive reefs, which render the approach to it very dangerous:  at sixteen miles to the northward of the cape there is a range, the HOLOTHURIA BANKS, that extend in an east and west direction for twenty-three miles; their north-east extent was not ascertained, but the western end, in latitude 13 degrees 32 minutes, and longitude 125 degrees 46 minutes 45 seconds, is narrow, and not more than five or six miles broad.

There is another range of reefs to the westward of the cape, that extends in a north and south direction for upwards of twenty miles; and about from three to five miles broad.  The water breaks on many parts of it.  Its north extremity, in latitude 13 degrees 41 1/2 minutes, is sixteen miles West 3/4 North from Troughton Island:  in this space the sea is quite clear, and from sixteen to twenty fathoms deep.  The narrowest part of the channel, between the reef and the peninsula, is at Point Gibson, where it is more than eight miles wide, and in mid-channel about twenty-three fathoms deep.

Between Cape Bougainville and Cape Voltaire is the ADMIRALTY GULF.  It is twenty-nine miles wide and twenty-two deep, independent of Port Warrender.  This gulf is thickly strewed with islands and reefs:  a group off Cape Voltaire was seen by the French and named by them the INSTITUTE ISLANDS, the three principal of which, of flat-topped shape, are called Descartes, Fenelon, and Corneille; besides these the Montesquieu Group, and Pascal and Condillac Islands, were distinguished.  On the eastern side of the gulf, near the shore, are OSBORN’S ISLANDS, which are high and rocky:  the southernmost is remarkable for its steep, precipitous form, and for its resemblance to Mount Cockburn in Cambridge Gulf.  There is also a conspicuous high bluff on the principal island, which appears to have been seen by the French.

In the offing is CASSINI ISLAND; it is rather low and level, and surrounded by cliffs and rocky shores:  on the eastern side are four sandy beaches, which are very much frequented by turtle:  a reef projects off its north end for a mile and a half.  The anchorage is good near the island, but the water is very deep.  The situation of its centre is in latitude 13 degrees 55 minutes 5 seconds, and longitude 125 degrees 42 minutes.

PORT WARRENDER is an excellent port, and affords good anchorage in the bay round Crystal Head, in which a vessel is quite land-locked; but equally secure anchorage may be had for five miles higher up the port, in from four to seven fathoms, mud.  It extends for six miles farther, but the depth in some parts is not more than two fathoms.