The Brouwer Route was a 17th-century route that was discovered and used by ships sailing from the African Cape of Good Hope to the Dutch East Indies base of Java. The route took ships south from the Cape (which is at 34° latitude south) into the Roaring Forties (at 40-50° latitude south), then east across the Indian Ocean, before turning northeast for Java. Thus it took advantage of the strong westerly winds for which the Roaring Forties are named, greatly increasing travel speed. The problem with the route, however, was that there was no accurate way at the time to determine longitude. The sighting of either Amsterdam Island or Saint Paul Island was the cue for ships to change direction and head north. However this was reliant on the captain's expertise.