Where is the sleeper shoal located in Seattle harbor where the depth is less than 10 fathoms?

The sleeper shoal is located off the northern end of Pier 66 in Seattle Harbor where the depth is less than 10 fathoms. This area is particularly important for navigation and safety in the harbor, as understanding the location of shoals helps in preventing grounding and other navigational hazards. The depth of less than 10 fathoms indicates a shallow area where vessels should exercise caution.

Pier 66 is situated in a part of the Seattle waterfront that is busy with ferry and cruise ship traffic, highlighting the significance of knowing the underwater topography for safe and efficient vessel movement. Mariners use this information to ensure that they maintain safe distances from shallow areas, helping to avoid accidents and ensure the safety of both vessels and their crews.

Other locations mentioned, such as near Duwamish Head, south of the Seattle Aquarium, and at the mouth of Elliott Bay, do not coincide with the known characteristics of sleeper shoal depth as correctly identified by the northern end of Pier 66. Therefore, the correct answer effectively communicates essential navigational information relevant to Seattle’s maritime safety and planning.