His reluctance to turn back when he reached Westernport was unquestionably due to the same cause.

The voyage in the whaleboat had not proved the strait.

It was still possible, though not at all probable, that the head of a deep gulf lay farther westward.

The subsequent circumnavigation of Tasmania by Bass and Flinders proved the strait, as did also Grant's voyage through it from the west in the Lady Nelson in 1800.
Hunter had no more evidence than that afforded by Bass's discoveries when he wrote, in his despatch to the Secretary of State: "He found an open ocean westward, and by the mountainous sea which rolled from that quarter, and no land discoverable in that direction, we have much reason to conclude that there is an open strait through." Hunter's "much reason to conclude" implies no more doubt about the strait than do the words of Bass, but the phrase does imply a recognition of the want of conclusive proof, creditable to the restrained judgment of both men.

Flinders also wrote: "There seemed to want no other proof of the existence of a passage than that of sailing positively through it," which is precisely what he set himself to do in Bass's company, as soon as he could secure an opportunity.