The Monkey Island SCUMM Bar: Trivia: Cogg Island’s Location and the Locke Smith Connection

According to Dave Grossman, the end goal of Cogg Island’s puzzle chain was to find Locke Smith’s mother’s golden key. Mother Smith had, apparently, been one of the island’s designers. Cogg was originally located on the south-east part of the map. Source: Returning to Monkey Island - Noclip Documentary.