Pierre Elliott Trudeau airport is the main entry to Montreal, about 15 miles away. Outside the airport baggage claim area go to the AirConnect stop, which is a free shuttle taking you to the railway stop for a 20 minute ride downtown. You can also take the 747 shuttle bus which runs all day every day, getting downtown in about 40 minutes while making 9 stops.
You can take a city bus downtown, but it involves 2 transfers. Must have exact change on city buses, but tickets can be bought on vending machines at metro stations, where you can buy unlimited mileage tickets for 3 days or a week, saving some money for budget travelers. A plastic Opus card can be reloaded indefinitely and will last for years.
There is no east-west thorofare that bypasses the island, so all traffic, even heavy trucks, have to cross the city, which has led to deteriorating roads and gridlock. The downtown area is inviting to pedestrians, and big chunks of central Montreal are blocked to cars during the summer festival season.
The extensive Montreal bus system covers all the island and crosses into Laval and Longueuil as well as the west island, and with a transfer it’s easy to get anywhere on a single fare.
The underground Montreal metro has been running since 1966, and is looking a bit worn. With 68 stations, the metro is divided into the orange, green, blue, and yellow line, and equipped with rubber wheels it is reasonably quiet. Trasfers are good on both bus and metro for the same fare, and the Metro runs under the St.Lawrence seaway to reach Laval and Longueuil.
Five commuter rail lines run to the edges of Montreal and beyond to suburban towns, with fares higher than bus or metro and non-transferrable. Skiers can take the commuter rail to Mont St.Hilaire.