The East Coast Trail is located on Newfoundland's Avalon Peninsula.
You can reach the island in one of two ways...
By Air
St. John's boasts an international airport with regularly scheduled flights direct from Halifax, Toronto and London. It is located about a 10 minute drive away from the city centre. You can rent a car from the airport, or take a taxi at a reasonable rate, however you can not pick up the local transit bus, Metrobus, from the airport.
By Water
You can take one of Marine Atlantic's superferries from North Sydney, Nova Scotia. You can take the ferry to one of two locations in Newfoundland. If you want to arrive closer to the Trail, on the East coast of the island, and don't mind the longer ferry ride, you might want to consider taking the Argentia ferry. This ferry, however, is only operational in the summer.
If you want a shorter ferry ride and don't mind a longer drive across the province (remember Newfoundland is a big island!), then you should consider taking the ferry to Port Aux Basques, on Newfoundland's Southwest Coast.
You can take your car or camper across on the ferry, or you can just walk on. A word to the wise, however, don't expect to rent a car from the Newfoundland ferry terminals. Do that before you come across, or take the DRL Bus to the Avalon Peninsula. Check schedules before leaving North Sydney.