A line drawn from the nearest part of Cape Catastrophe to Cape Spencer will be forty-eight miles long, and so much is the entrance of the gulph in width.  Gambier’s Isles lie not far from the middle of the line; and if we measure upward from them, the gulph will be found, without regard to the small windings, to extend one hundred and eighty-five miles into the interior of the country.  For the general exactness of its form in the chart I can answer with tolerable confidence, having seen all that is laid down, and, as usual, taken every angle which enters into the construction.  Throughout the whole extent of the shores the water line was almost every where distinguished; the only exceptions being small portions at the head of Hardwicke and Louth Bays, of a bight near Point Lowly, and of the low land at the back of the great Eastern Shoal.

At noon, when off Cape Spencer, the wind became variable and light, with very hazy, cloudy weather; and the mercury in my marine barometer had fallen two-tenths of an inch.  At six in the evening a breeze sprung up at west-north-west; and as I expected a gale would come on, and that as usual it would veer to the south-west, we ceased to follow the coast beyond Cape Spencer, and steered for the land seen in the southern quarter.  The Althorp Isles were passed at eight o’clock, at the distance of eight or nine miles; and the wind being fresh at west, we made short trips during the night between the two lands, not knowing what might be in the space to leeward.  At daylight [SUNDAY 21 MARCH 1802] the ship was nearly in mid-channel, between the southern land and Cape Spencer, and nothing was seen to the eastward.  It then blew a fresh gale at south-west, with much sea running; we stretched south-west under close-reefed top-sails, to get under the lee of the southern land; and at eight o’clock, when the largest Althorp Isle bore N. 32 deg.  W., it was distant six or seven miles to the south, and extended from S. 61 deg.  W. to 79 deg.  E. as far as the eye could reach.  It was rather high and cliffy; but there was nothing by which to judge of its connection with the main.

At ten o’clock we were close under the land; and finding the water tolerably smooth, had shortened sail with the intention of anchoring near a small, sandy beach; but the situation proving to be too much exposed, we steered eastward along the shore under two close-reefed topsails and fore-sail, the wind blowing strong in squalls from the south-west.  The furthest land seen ahead at noon was a projecting point, lower than the other cliffs; it bore E. 7 deg.  S., four leagues, and and lies in 35 deg. 33’ south and 137 deg. 41’ east.  It was named Point Marsden, in compliment to the second secretary of the Admiralty; and beyond it the coast was found to trend southward into a large bay containing three coves, any one of which promised good shelter from the gale.  This was called NEPEAN BAY. in compliment to the first secretary (now Sir Evan Nepean,