At an altitude of 788 metres (2,585 ft) above sea level, the pass provides a passage between Dunedoo and Coolah in the southwest and Premer and the Liverpool Plains in the north.

After receiving Governor Brisbane's approval for the exploration Cunningham left Sydney on 31 March 1823, crossing the Nepean River on his way to Bathurst.

The following memorandum, written on parchment, was enclosed in a bottle, and buried under a marked tree in the Pandora Pass:[3] After a very laborious and harassing journey from Bathurst, since April last, a party, consisting of five persons, under the direction of Allan Cunningham, H.M. Botanist (making the sixth individual), having failed of finding a route to Liverpool Plains, whilst tracing the south base of the Barrier Mountains (before us north), so far as fifty miles to the eastward of this spot, at length upon prosecuting their research under this great mountain belt, in a westerly direction, reached this valley, and discovered a practicable and easy passage through a low part of the mountain belt, north by west from this tree, to the very extensive levels connected with the abovementioned plains, of which the southernmost of the chain is distant about eleven or twelve miles (by estimation), N.N.W.

from this valley, and to which a line of trees has been carefully marked, thus opening an unlimited, unbounded, seemingly well-watered country, N.N.W., to call forth the exertions of the industrious agriculturist and grazier, for whose benefit the present labours of the party have been extended.

The party in the earlier and middle stages of their expedition encountered many privations and local difficulties of travelling to, and in their return from the eastward; in spite, however, of these little evils, 'a hope at the bottom,' or, at this almost close of their journey, an encouragement induced them to persevere westerly a limited distance, and thus it was this passage was discovered.

Due east and west by compass from this tree, in a direct line (by odometrical admeasurement) were planted the fresh stones of peaches, brought from the colony in April last, with every good hope that their produce will one day or other afford some refreshment to the weary farmer, whilst on his route beyond the bourne of the desirable country north of Pandora's Pass.

A like planting took place on the plains, twelve miles distance north at the last marked trees, with similar good wishes for their growth.

Buried for the information of the first farmer who may venture to advance so far to the northwards as this vale, of whom it is requested this document may not be destroyed, but carried to the settlement of Bathurst, after opening the bottle.