Van Densp Inlet branches off from the northern end of the channel to incise Cortes Island from the northwest.

The southern boundary of Sutil Channel, where it joins the Strait of Georgia, is defined as a line between Francisco Point, at the southeast end of Quadra Island, to Sutil Point, the southern end of Cortes Island.

Sometimes Cape Mudge instead of Francisco Point is mentioned as the southern end of Quadra Island.

[4] Desolation Sound, which strictly defined does not directly connect to Sutil Channel, is sometimes used loosely as all the waters north of Cape Mudge and Sarah Point, including Sutil Channel and Discovery Passage.

The Penn Islands of Sutil Channel delineate part of the northern limit of the Salish Sea.