Final answer:
Lake Mjøsa is the lake that borders Lillehammer, the site of the 1994 Winter Olympics in Norway and is the largest lake in the country.
Step-by-step explanation:
The lake that borders Lillehammer, the site of the 1994 Winter Olympics in Norway, is Lake Mjøsa. It is the largest lake in Norway and provides a picturesque backdrop to the Olympic events. Lillehammer, being a city in Norway, is surrounded by beautiful landscapes, and Lake Mjøsa is a significant part of its natural environment. The city gained an international spotlight during the Olympics and has since been known for its winter sports facilities and cultural heritage.