The Sound is located at a confluence of the cold Labrador Currents and the warm Gulf Stream. This creates a unique coastal habitat representing the southern range for Northern Atlantic species and the northern range for Mid-Atlantic species. Nantucket Sound has much biological diversity and contains habitats that range from open sea to salt marshes, as well as warm-water beaches on the Cape and Islands coasts.
Nantucket Sound is well known for the numerous shoals within its boundaries.[2]