He accompanied his brother, as we have already noted, in two important expeditions, and in 1871 he took charge of a private expedition to the eastward in search of pastoral country.

Owing to a late start, he and his party were compelled to make for the coast when they had reached latitude 31 degrees south, longitude 123 degrees east.

This course led them to Mount Ragged, whence, proceeding westerly, they returned to Perth by way of Esperance, having penetrated inland six hundred miles and found a considerable area of good country.
In 1879, Alexander Forrest led an expedition from the De Grey River to the now customary goal, the overland telegraph line of South Australia.
He left the De Grey on the 25th of February, and reached Beagle Bay on the 10th of April, the country passed over being like most land in the immediate neighbourhood of the coast, poor and indifferent.
From Beagle Bay he followed the coast round to the Fitzroy, and proceeded up that river until he encountered a range, which was named the King Leopold Range.

Here the party left the Fitzroy, of which river Forrest speaks very highly, and struck north, looking for a pass through the range.

It proved to be very rough and precipitous, and when at last they reached the sea, they found themselves in an angle, wedged in between the sea and the range, romantic and picturesque, according to Forrest's description, but quite impassible.