The Sea to Sky Highway, British Columbia Highway 99, is the only practical road through the corridor. From Vancouver, Lions Bay is about 30 minutes in light traffic and Britannia Beach is closer to 45 minutes. Summer weekends can be much slower.
Public transit reaches Lions Bay from West Vancouver, but most of the parks and communities farther north are not useful by bus. If you want to visit Porteau Cove, Britannia Beach, or the higher trailheads, come by car.