Princess Bay on Portland Island is likely the most popular anchorage in the Gulf Islands National Park Reserve. There’s plenty of room for lots of boats and the mud bottom does a great job of keeping you in place. Really, the only big downside here is the wash from the large BC Ferries that ply the route between Vancouver and Vancouver Island. A dinghy dock is close by, the swimming is good and there are many kilometers of trails to get you off your boat. During the summer get up early for the great sunrises.
Royal Cove on the north side of Portland Island has room for a small number of boats, many of which stern tie to the shore. This area has a dinghy dock as well. North winds can be a problem and once again the ferry wash may be unpleasant but it’s hard to know as conditions change.