British Columbia officially uses the Canadian Dollar. Another name people know for this is the loonie. A loonie is actually a one dollar coin. A two dollar coin is called a toonie.
Since the majority of the population center is so close to the United States, a high percentage of stores will exchange US dollars for Canadian dollars. Banks will offer a better exchange rate, though.
Credit Cards and ATMs
Credit Cards are generally accepted everywhere. Debit cards can be a bit more of a hassle. If a person does not have a Canadian bank issued debit card, it will generally not be accepted in most places, including ATMs. Traveler's checks are another option. They are generally accepted by bigger businesses.