In the southmost island, Vattersay, is uninhabited, and the men take out provisions and everything they want with them, and they fish there during the six weeks of the fishing.
"Second Shetland Truck System Report"
William Guthrie
Most is sometimes added to a substantive, as, topmost, southmost.
"A Grammar of the English Tongue"
Samuel Johnson
Branching off from F12A, and running back in a long curve into the enemy's next line of defence, was a trench known as F13. It was necessary, if F12A was to be held by us, that the southmost stretch of F13 should be cleared of the enemy.
"The Fifth Battalion Highland Light Infantry in the War 1914-1918"
F.L. Morrison