The Portland Canal was first explored .
The Portland Canal was first named in July 1793 by Captain George Vancouver in honour of William Henry Cavendish Bentinck , 3rd Duke of Portland ( 1738 - 1808 ) , Home Secretary from 1794 to 1801 .
The Portland Canal was first explored and named in July 1793 by Captain George Vancouver in honour of William Henry Cavendish Bentinck , 3rd Duke of Portland ( 1738 - 1808 ) , Home Secretary from 1794 to 1801 .