Inside passage means different things to different people.
The very broad definition (which the cruise industry uses), is the area between Seattle/Vancouver and Juneau along the coast not in the open ocean.
Arguably if you are going to Juneau/Skagway/Ketchikan/Endicott Arm you are in the inside passage.
That being said, when a lot of cruisers say inside passage, they mean the area between Vancouver Island and mainland British Columbia.
In order to take the "preferred" route, you need to Leave out of Vancouver (with some exceptions) and have a ship that can fit under the under the Lions Gate Bridge.
I marched up the attached picturebwith the broad definition and "preferred"(Inside of Vancouver Island) definition.
SEA_KTN_ENC_JNU_SGY_XIP_YVJ_SEA_282x216-1.avif SEA_KTN_ENC_JNU_SGY_XIP_YVJ_SEA_282x216.avif