There is apparently a bus that goes from the airport to the ferry. https://www.rome2rio.com/s/Vancouver...Ferry-Terminal according to google it'll take about 50 minutes. I'm pretty sure the skytrain doesn't go to the ferry in Tsawassen. You're trying to get to the island, right? Tswassen goes to Nanaimo and Victoria, I think. There's supposed to be a ferry terminal in Vancouver itself, which might be reachable by skytrain.