Name a region in Australia known for its cool-climate Pinot Noir.

Tasmania is recognized as a notable region in Australia for its cool-climate Pinot Noir due to its unique geographical and climatic conditions. The island's cooler temperatures, combined with a longer growing season, allow for the development of complex flavors and crisp acidity typical of high-quality Pinot Noir grapes. The region is characterized by its maritime climate, with influences from the surrounding seas that help moderate temperatures and provide an ideal environment for this delicate grape variety.

In contrast, other regions mentioned, such as Barossa Valley, are known for warmer climates, which are more suited for grape varieties that thrive in higher temperatures, like Shiraz. Sydney, being a metropolitan area, does not serve as a prominent wine-growing region for this varietal. Similarly, while Margaret River produces various varietals, it is primarily known for its Cabernet Sauvignon and Chardonnay, rather than Pinot Noir, especially from cooler climate segments. Thus, Tasmania stands out as the most suitable choice for those seeking high-quality cool-climate Pinot Noir.