Question: HMAS "Platypus" was a submarine depot ship and base ship operated by the Royal Australian Navy (RAN), ordered prior to World War I to support the Australian submarines originally known as just AE1, HMAS "AE1, was an "E"-class submarine of which organization?
Sentence (from "HMAS AE1"): The wreck of the submarine has never been found, despite several searches.
Relevant evidence: No