Final answer:
The Puget Lowlands are known for their unique features, which include Puget Sound, a network of waterways, and many islands, contributing to the region's ecological and economic activities.
Step-by-step explanation:
The region characterized by a sound, many islands, and a system of waterways and bays is the Puget Lowlands. This area is part of the Pacific Northwest and includes such features as Puget Sound, an extensive network of channels, inlets, and islands. It is particularly known for its unique and complex system of waterways that play a significant role in the ecosystem and the economy of the region, including transportation, fishing, and tourism.