The vessel was originally ordered by the United Kingdom's Royal Navy as HMS H20, but was handed over to Chile in 1917 as H6.

Fresia was a single-hulled submarine, with a pressure hull divided into five watertight compartments.

The H-class submarines had a crew of 22 officers and enlisted men.

The boat had a capacity of 17.5 long tons (17.8 t) of fuel oil.

[1] H20 was a H-class submarine built by Fore River Yard of Quincy, Massachusetts.